From 217ec33aefaedb17e8eaaa0e1697bfccb27a17cc Mon Sep 17 00:00:00 2001 From: = <=516843958@qq.com> Date: Thu, 25 Jan 2018 15:44:59 +0800 Subject: [PATCH 1/3] initc --- .test.py.swp | Bin 0 -> 12288 bytes .../origin__new-bird-species-20171213.html | 206 ++++++++++++++++++ main.py | 29 +++ origin.html | 206 ++++++++++++++++++ sub_test.html | 9 + test.html | 9 + test.py | 8 + 7 files changed, 467 insertions(+) create mode 100644 .test.py.swp create mode 100644 html/pages/origin__new-bird-species-20171213.html create mode 100644 main.py create mode 100644 origin.html create mode 100644 sub_test.html create mode 100644 test.html create mode 100644 test.py diff --git a/.test.py.swp b/.test.py.swp new file mode 100644 index 0000000000000000000000000000000000000000..71b6bc0024fe1d4e8e4a1a03bbb581d462c06675 GIT binary patch literal 12288 zcmeI&!Aiq07zglg1Hp?ZdY9N;TA1yef@9!8@FM7O9=wcpP1nlW#x$eW%ih74@Fjc} zeHFisD#Oc|x4}Q~ktX?)G{0MEg5JaJy|{EQh|2-dpc_AS?gs7SG0}7JRQIkevt$~Z zB%7{F^g`eGeUF#*N*NTn4n0+wIL}VC^g};LW{IghBMalIYTaTOhX4dN6xgHl{#mb{ z)Ui&)(cx&r`ACNV1Rwwb2tWV=5P$##wpqZa7A^Py?dA}>P2KuaH%(L!fB*y_009U< z00Izz00bZa0SIiNfFBa=>=Rvc)c^l~zW=|t{mJpc@y_wa@yapcSmtiwS@FscfB*y_ z009U<00Izz00bZafqx4KAtJZbiIH|OPg7r44wZ?CMXqFKTg5yWFK@KRCY@PbtF#>9 z7a|%`lP#`9m`~iMWjn+z?z_n+^HgTWHuA+d#Jh<4iAN&k*4O1Zb7h;=Ep)Sm8WKf1 RPsPgZdXc0m*XDP5`UaYVV)g(4 literal 0 HcmV?d00001 diff --git a/html/pages/origin__new-bird-species-20171213.html b/html/pages/origin__new-bird-species-20171213.html new file mode 100644 index 00000000..6ad2d83b --- /dev/null +++ b/html/pages/origin__new-bird-species-20171213.html @@ -0,0 +1,206 @@ + + + New Bird Species Arises From Hybrids, as Scientists Watch | Quanta Magazine + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ + +
Abstractions blog

New Bird Species Arises From Hybrids, as Scientists Watch

The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+
The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)
The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

+
\ No newline at end of file diff --git a/main.py b/main.py new file mode 100644 index 00000000..f5703b14 --- /dev/null +++ b/main.py @@ -0,0 +1,29 @@ +#!-*-coding:utf-8-*- +import requests +import os +from readability import Document +#url = "https://www.quantamagazine.org/new-bird-species-arises-from-hybrids-as-scientists-watch-20171213/" +#response = requests.get(url) +with open("origin.html","r") as f: + text = f.read() +doc = Document(text) +summary = doc.summary() +content = doc.content() +title = doc.title() +short_title = doc.short_title() +dir_name = os.path.join(os.path.dirname(__name__),'html') +fp = os.path.join(dir_name,"summary_new-bird-species-20171213.html") +with open(fp,'w') as f: + f.write(summary) +fp = os.path.join(dir_name,"content_new-bird-species-20171213.html") +with open(fp,'w') as f: + f.write(content) +fp = os.path.join(dir_name,"short_title__new-bird-species-20171213.html") +with open(fp,'w') as f: + f.write(short_title) +fp = os.path.join(dir_name,"title__new-bird-species-20171213.html") +with open(fp,'w') as f: + f.write(title) +fp = os.path.join(dir_name,"origin__new-bird-species-20171213.html") +with open(fp,'w') as f: + f.write(text) diff --git a/origin.html b/origin.html new file mode 100644 index 00000000..6ad2d83b --- /dev/null +++ b/origin.html @@ -0,0 +1,206 @@ + + + New Bird Species Arises From Hybrids, as Scientists Watch | Quanta Magazine + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ + +
Abstractions blog

New Bird Species Arises From Hybrids, as Scientists Watch

The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+
The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)
The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

+
\ No newline at end of file diff --git a/sub_test.html b/sub_test.html new file mode 100644 index 00000000..c338188c --- /dev/null +++ b/sub_test.html @@ -0,0 +1,9 @@ +

+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+

+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+
\ No newline at end of file diff --git a/test.html b/test.html new file mode 100644 index 00000000..b6b28f31 --- /dev/null +++ b/test.html @@ -0,0 +1,9 @@ +
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+
\ No newline at end of file diff --git a/test.py b/test.py new file mode 100644 index 00000000..5ba71ba7 --- /dev/null +++ b/test.py @@ -0,0 +1,8 @@ +from readability import Document + +with open("test.html","r") as fp: + text = fp.read() +doc = Document(text) +summary = doc.summary() +with open("sub_test.html","w") as f: + f.write(summary) From 3649e9c61d4297ed3421fdc6c6efc40b27b5868f Mon Sep 17 00:00:00 2001 From: = <=516843958@qq.com> Date: Thu, 25 Jan 2018 16:29:54 +0800 Subject: [PATCH 2/3] one --- ...rd-species-20171213.html => new-bird.html} | 0 html/result/content_new-bird.html | 20 +++++++ main.py | 56 +++++++++++-------- 3 files changed, 53 insertions(+), 23 deletions(-) rename html/pages/{origin__new-bird-species-20171213.html => new-bird.html} (100%) create mode 100644 html/result/content_new-bird.html diff --git a/html/pages/origin__new-bird-species-20171213.html b/html/pages/new-bird.html similarity index 100% rename from html/pages/origin__new-bird-species-20171213.html rename to html/pages/new-bird.html diff --git a/html/result/content_new-bird.html b/html/result/content_new-bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_new-bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/main.py b/main.py index f5703b14..d601c429 100644 --- a/main.py +++ b/main.py @@ -1,29 +1,39 @@ #!-*-coding:utf-8-*- import requests import os +import hashlib +import argparse from readability import Document #url = "https://www.quantamagazine.org/new-bird-species-arises-from-hybrids-as-scientists-watch-20171213/" #response = requests.get(url) -with open("origin.html","r") as f: - text = f.read() -doc = Document(text) -summary = doc.summary() -content = doc.content() -title = doc.title() -short_title = doc.short_title() -dir_name = os.path.join(os.path.dirname(__name__),'html') -fp = os.path.join(dir_name,"summary_new-bird-species-20171213.html") -with open(fp,'w') as f: - f.write(summary) -fp = os.path.join(dir_name,"content_new-bird-species-20171213.html") -with open(fp,'w') as f: - f.write(content) -fp = os.path.join(dir_name,"short_title__new-bird-species-20171213.html") -with open(fp,'w') as f: - f.write(short_title) -fp = os.path.join(dir_name,"title__new-bird-species-20171213.html") -with open(fp,'w') as f: - f.write(title) -fp = os.path.join(dir_name,"origin__new-bird-species-20171213.html") -with open(fp,'w') as f: - f.write(text) +SAVE_DIR = os.path.join(os.path.dirname(__name__), "html", "result") + +def parse_summary(filename=None,url=None): + if filename: + with open(filename,"r") as f: + html = f.read() + n = "content_%s"%os.path.basename(filename) + if url: + html = request.get(url) + n = "url_content_%s_.html"%hashlib.md5(url.encode("utf-8")).hexdigest()[0:6] + doc = Document(html) + summary = doc.summary() + fn = os.path.join(SAVE_DIR, n) + with open(fn, 'w') as f: + f.write(summary) + + +if __name__ == "__main__": + parse = argparse.ArgumentParser() + parse.add_argument('-f',"--file",help="set file to parse") + parse.add_argument("-l", "--url", help="set url link to parse") + args = parse.parse_args() + if args.file: + filename = args.file + parse_summary(filename=filename) + print("parse success") + else : + if args.url: + url = args.url + parse_summary(url=url) + print("parse success") \ No newline at end of file From 04c4794bbc40d246bc3b2eb2ec831b8d98ed6d55 Mon Sep 17 00:00:00 2001 From: = <=516843958@qq.com> Date: Wed, 31 Jan 2018 16:37:20 +0800 Subject: [PATCH 3/3] add test --- .test.py.swp | Bin 12288 -> 0 bytes html/pages/delete10_new_bird.html | 30 +++ html/pages/delete11_new_bird.html | 30 +++ html/pages/delete12_new_bird.html | 43 +++++ html/pages/delete2_new_brid.html | 207 +++++++++++++++++++++ html/pages/delete3_new_bird.html | 207 +++++++++++++++++++++ html/pages/delete4_new_bird.html | 188 +++++++++++++++++++ html/pages/delete5_new_bird.html | 83 +++++++++ html/pages/delete6_new_bird.html | 30 +++ html/pages/delete7_new_bird.html | 17 ++ html/pages/delete8_new_bird.html | 30 +++ html/pages/delete9_new_bird.html | 32 ++++ html/pages/delete_new_brid.html | 207 +++++++++++++++++++++ html/result/content_delete10_new_bird.html | 20 ++ html/result/content_delete11_new_bird.html | 20 ++ html/result/content_delete12_new_bird.html | 20 ++ html/result/content_delete2_new_brid.html | 20 ++ html/result/content_delete3_new_bird.html | 20 ++ html/result/content_delete4_new_bird.html | 20 ++ html/result/content_delete5_new_bird.html | 20 ++ html/result/content_delete6_new_bird.html | 20 ++ html/result/content_delete7_new_bird.html | 9 + html/result/content_delete8_new_bird.html | 20 ++ html/result/content_delete9_new_bird.html | 20 ++ html/result/content_delete_new_brid.html | 20 ++ html/result/url_content_a95dbd_.html | 147 +++++++++++++++ main.py | 2 +- tmp.py | 23 +++ 28 files changed, 1504 insertions(+), 1 deletion(-) delete mode 100644 .test.py.swp create mode 100644 html/pages/delete10_new_bird.html create mode 100644 html/pages/delete11_new_bird.html create mode 100644 html/pages/delete12_new_bird.html create mode 100644 html/pages/delete2_new_brid.html create mode 100644 html/pages/delete3_new_bird.html create mode 100644 html/pages/delete4_new_bird.html create mode 100644 html/pages/delete5_new_bird.html create mode 100644 html/pages/delete6_new_bird.html create mode 100644 html/pages/delete7_new_bird.html create mode 100644 html/pages/delete8_new_bird.html create mode 100644 html/pages/delete9_new_bird.html create mode 100644 html/pages/delete_new_brid.html create mode 100644 html/result/content_delete10_new_bird.html create mode 100644 html/result/content_delete11_new_bird.html create mode 100644 html/result/content_delete12_new_bird.html create mode 100644 html/result/content_delete2_new_brid.html create mode 100644 html/result/content_delete3_new_bird.html create mode 100644 html/result/content_delete4_new_bird.html create mode 100644 html/result/content_delete5_new_bird.html create mode 100644 html/result/content_delete6_new_bird.html create mode 100644 html/result/content_delete7_new_bird.html create mode 100644 html/result/content_delete8_new_bird.html create mode 100644 html/result/content_delete9_new_bird.html create mode 100644 html/result/content_delete_new_brid.html create mode 100644 html/result/url_content_a95dbd_.html create mode 100644 tmp.py diff --git a/.test.py.swp b/.test.py.swp deleted file mode 100644 index 71b6bc0024fe1d4e8e4a1a03bbb581d462c06675..0000000000000000000000000000000000000000 GIT binary patch literal 0 HcmV?d00001 literal 12288 zcmeI&!Aiq07zglg1Hp?ZdY9N;TA1yef@9!8@FM7O9=wcpP1nlW#x$eW%ih74@Fjc} zeHFisD#Oc|x4}Q~ktX?)G{0MEg5JaJy|{EQh|2-dpc_AS?gs7SG0}7JRQIkevt$~Z zB%7{F^g`eGeUF#*N*NTn4n0+wIL}VC^g};LW{IghBMalIYTaTOhX4dN6xgHl{#mb{ z)Ui&)(cx&r`ACNV1Rwwb2tWV=5P$##wpqZa7A^Py?dA}>P2KuaH%(L!fB*y_009U< z00Izz00bZa0SIiNfFBa=>=Rvc)c^l~zW=|t{mJpc@y_wa@yapcSmtiwS@FscfB*y_ z009U<00Izz00bZafqx4KAtJZbiIH|OPg7r44wZ?CMXqFKTg5yWFK@KRCY@PbtF#>9 z7a|%`lP#`9m`~iMWjn+z?z_n+^HgTWHuA+d#Jh<4iAN&k*4O1Zb7h;=Ep)Sm8WKf1 RPsPgZdXc0m*XDP5`UaYVV)g(4 diff --git a/html/pages/delete10_new_bird.html b/html/pages/delete10_new_bird.html new file mode 100644 index 00000000..f5fd257a --- /dev/null +++ b/html/pages/delete10_new_bird.html @@ -0,0 +1,30 @@ + + +
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/pages/delete11_new_bird.html b/html/pages/delete11_new_bird.html new file mode 100644 index 00000000..410006e6 --- /dev/null +++ b/html/pages/delete11_new_bird.html @@ -0,0 +1,30 @@ + + +
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+ +

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/pages/delete12_new_bird.html b/html/pages/delete12_new_bird.html new file mode 100644 index 00000000..6d822f6f --- /dev/null +++ b/html/pages/delete12_new_bird.html @@ -0,0 +1,43 @@ +
+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
+ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
+
\ No newline at end of file diff --git a/html/pages/delete2_new_brid.html b/html/pages/delete2_new_brid.html new file mode 100644 index 00000000..bc218283 --- /dev/null +++ b/html/pages/delete2_new_brid.html @@ -0,0 +1,207 @@ + + + + New Bird Species Arises From Hybrids, as Scientists Watch | Quanta Magazine + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ + +
Abstractions blog

New Bird Species Arises From Hybrids, as Scientists Watch

The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

+
\ No newline at end of file diff --git a/html/pages/delete3_new_bird.html b/html/pages/delete3_new_bird.html new file mode 100644 index 00000000..ca542e6a --- /dev/null +++ b/html/pages/delete3_new_bird.html @@ -0,0 +1,207 @@ + + + + New Bird Species Arises From Hybrids, as Scientists Watch | Quanta Magazine + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
+ + +
The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

+
\ No newline at end of file diff --git a/html/pages/delete4_new_bird.html b/html/pages/delete4_new_bird.html new file mode 100644 index 00000000..7e6aac8f --- /dev/null +++ b/html/pages/delete4_new_bird.html @@ -0,0 +1,188 @@ + + + + New Bird Species Arises From Hybrids, as Scientists Watch | Quanta Magazine + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

+
\ No newline at end of file diff --git a/html/pages/delete5_new_bird.html b/html/pages/delete5_new_bird.html new file mode 100644 index 00000000..eb5f8c34 --- /dev/null +++ b/html/pages/delete5_new_bird.html @@ -0,0 +1,83 @@ + + +
The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

+
\ No newline at end of file diff --git a/html/pages/delete6_new_bird.html b/html/pages/delete6_new_bird.html new file mode 100644 index 00000000..ef6b0034 --- /dev/null +++ b/html/pages/delete6_new_bird.html @@ -0,0 +1,30 @@ +
The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/pages/delete7_new_bird.html b/html/pages/delete7_new_bird.html new file mode 100644 index 00000000..41914a91 --- /dev/null +++ b/html/pages/delete7_new_bird.html @@ -0,0 +1,17 @@ +
+ +
The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+ +
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+
+ + + +
\ No newline at end of file diff --git a/html/pages/delete8_new_bird.html b/html/pages/delete8_new_bird.html new file mode 100644 index 00000000..4c01e719 --- /dev/null +++ b/html/pages/delete8_new_bird.html @@ -0,0 +1,30 @@ +
The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/pages/delete9_new_bird.html b/html/pages/delete9_new_bird.html new file mode 100644 index 00000000..5a8f0e06 --- /dev/null +++ b/html/pages/delete9_new_bird.html @@ -0,0 +1,32 @@ + + +
+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+
+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
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Abstractions blog

New Bird Species Arises From Hybrids, as Scientists Watch

The rapid, unorthodox emergence of a new finch in the Galápagos hints that speciation isn’t rare. New hybrid species may quietly appear and disappear without anyone noticing.
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It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

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Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

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Eyewitnesses to Speciation

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In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

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The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)
The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

The new lineage of birds began when a male Geospiza conirostris finch marooned on Daphne Major island mated with a native G. fortis females. (These photos show birds representative of those species, and not the actual parental birds.)

+

Lip Kee Yap (Geospiza conirostris);  David Cook (G. fortis)

+

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+
+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+
+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+

Comment on this article

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\ No newline at end of file diff --git a/html/result/content_delete10_new_bird.html b/html/result/content_delete10_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete10_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete11_new_bird.html b/html/result/content_delete11_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete11_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete12_new_bird.html b/html/result/content_delete12_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete12_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete2_new_brid.html b/html/result/content_delete2_new_brid.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete2_new_brid.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete3_new_bird.html b/html/result/content_delete3_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete3_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete4_new_bird.html b/html/result/content_delete4_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete4_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete5_new_bird.html b/html/result/content_delete5_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete5_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete6_new_bird.html b/html/result/content_delete6_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete6_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete7_new_bird.html b/html/result/content_delete7_new_bird.html new file mode 100644 index 00000000..c338188c --- /dev/null +++ b/html/result/content_delete7_new_bird.html @@ -0,0 +1,9 @@ +

+

It’s not every day that scientists observe a new species emerging in real time. Charles Darwin believed that speciation probably took place over hundreds if not thousands of generations, advancing far too gradually to be detected directly. The biologists who followed him have generally defaulted to a similar understanding and have relied on indirect clues, gleaned from genomes and fossils, to infer complex organisms’ evolutionary histories.

+

Some of those clues suggest that interbreeding plays a larger role in the formation of new species than previously thought. But the issue remains contentious: Hybridization has been definitively shown to cause widespread speciation only in plants. When it comes to animals, it has remained a hypothesis (albeit one that’s gaining increasing support) about events that typically occurred in the distant, unseen past.

+

Until now. In a paper published last month in Science, researchers reported that a new animal species had evolved by hybridization — and that it had occurred before their eyes in the span of merely two generations. The breakneck pace of that speciation event turned heads both in the scientific community and in the media. The mechanism by which it occurred is just as noteworthy, however, because of what it suggests about the undervalued role of hybrids in evolution.

+

+

Eyewitnesses to Speciation

+

In 1981, Peter and Rosemary Grant, the famous husband-and-wife team of evolutionary biologists at Princeton University, had already been studying Darwin’s finches on the small Galápagos island Daphne Major for nearly a decade. So when they spotted a male bird that looked and sounded different from the three species residing on the island, they immediately knew he didn’t belong. Genetic analysis showed he was a large cactus finch (Geospiza conirostris) from another island, either Española or Gardner, more than 60 miles away — too great a distance for the bird to fly home.

+

Tracking the marooned male bird’s activity, the Grants observed him as he mated with two female medium ground finches (G. fortis) on Daphne and produced hybrid offspring. Such interbreeding by isolated animals in the wild is not uncommon, though biologists have usually dismissed it as irrelevant to evolution because the hybrids tend to be unfit. Often they cannot reproduce, or they fail to compete effectively against established species and quickly go extinct. Even when the hybrids are fertile and fit, they frequently get reabsorbed into the original species by mating with their parent populations.

+
\ No newline at end of file diff --git a/html/result/content_delete8_new_bird.html b/html/result/content_delete8_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete8_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete9_new_bird.html b/html/result/content_delete9_new_bird.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete9_new_bird.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/content_delete_new_brid.html b/html/result/content_delete_new_brid.html new file mode 100644 index 00000000..d2f4c4af --- /dev/null +++ b/html/result/content_delete_new_brid.html @@ -0,0 +1,20 @@ +

But something different happened with the hybrids on Daphne: When they matured, they became a population distinct from Daphne’s other bird species by inbreeding extensively and exclusively — siblings mating with siblings, and parents mating with their offspring.

+

In short, an incipient hybrid species, which the researchers dubbed the Big Bird lineage, had emerged within two generations. Today, six generations have passed, and the island is home to around 30 Big Bird finches. “If you were a biologist none the wiser to what had happened,” said Leif Andersson, a geneticist at Uppsala University in Sweden and one of the study’s co-authors, “and you started studying these birds, you’d think there were four different species on the island.”

+

Where Hybrids Thrive

+

On Daphne Major, the conditions may have been just right for hybrid speciation. “It shows what is possible, given the right circumstances,” Peter Grant said, and it sends “a valuable message about the importance of rare and unpredictable events in evolution. These have probably been underestimated.”

+

The Big Bird lineage became reproductively isolated so quickly because those birds could not successfully attract mates among the island’s resident species, which preferred their own kind. Big Bird finches couldn’t pass muster: They had relatively large beaks for their body size, and they boasted a unique song. These differences prevented gene flow between the hybrids and the native medium ground finches from which they had descended, leading to a distinct hybrid population. (In their Science paper, the Grants and their colleagues noted that the species status of Big Bird finches is still unofficial because no one has yet tested whether the birds will breed with their ancestral finches on Española and Gardner. But they cited reasons to suspect that the Big Bird lineage is reproductively isolated from them as well.)

+

+

The physical differences in the hybrid lineage also made them competitive. The size and shape of the Big Birds’ beaks placed them squarely in their own ecological niche, allowing them to eat certain types of seeds their competitors could not. “The data is consistent with selection having taken place,” Andersson said.

+

The fact that this niche was available for Big Bird to occupy is likely a result of the particularly young, isolated and often extreme environment of the Galápagos. “Conditions on the islands really help drive the speciation process,” said Scott Edwards, an ornithologist at Harvard University.

+

The same might be said for small and isolated environments elsewhere, such as mountaintops or ponds. By contrast, speciation isn’t likely to occur this way in less isolated regions, said Trevor Price, an ecologist at the University of Chicago. In those areas, where competition for resources is already fierce, a new hybrid species like Big Bird would find no niche for itself.

+

But hybrid species may have had more widespread opportunities to establish themselves in the past. Perhaps, Price suggested, this rapid production of species could have occurred in the aftermath of the meteorite impact that caused mass extinction on Earth millions of years ago. At that time, there were resources and potential niches, and not enough species to fill them.

+

Fractal Speciation

+

Some experts think that even today hybrid speciation may be far from rare. Under the most commonly accepted speciation model, called allopatric speciation, populations get geographically separated — by a change in a river’s course, say, or the formation of a mountain, or diverging migrations —  and then adapt to distinct competitors and environments over long periods. If the groups ever meet again, they may no longer be similar enough to interbreed.

+

But very fast hybrid speciation events like the one the Grants saw on Daphne may often occur in bursts — only to end with the new species dying out before we have time to observe it. “Speciation is common. It’s happening all around us,” said James Mallet, an evolutionary biologist at Harvard University. “It’s just that usually we don’t recognize the divergent lineages that are appearing as separate species.”

+

He continued, “I believe that speciation is more of a continuum than people have been thinking.” At one extreme, species can be cleanly divided from one another, with no interbreeding and exchange of genes. But to greater or lesser degrees, hybridization could also allow genes to flow into a species from others, and the resulting hybrids could sometimes develop an identity of their own, even if only temporarily.

+

Mallet argues that hybrid species could very well be appearing all the time, only to collapse and disappear just as quickly, with the hybrids either going extinct or being absorbed back into a parent population. “To me, that shows the abundance of opportunities for speciation,” he said. Just because many hybrids go extinct — a fate that is still very likely to befall the Big Bird lineage, according to Mallet — doesn’t mean that hybridization is not a real source of new species in nature.

+

+

Instead, he sees speciation as an almost fractal process that can be observed in ecosystems over different timescales. “If you look at the macro level over millions of years,” Mallet said, “you’ll see a few species evolving and going extinct.” But at the micro level, on the order of dozens of years or less, species may be forming and dissolving all the time. Most biologists simply don’t have the long-term data to show it, he said.

+

What made it possible to identify such an event in Darwin’s finches was the Grants’ decades of careful fieldwork, followed by detailed genomics studies. The new paper illustrates “the value of continuous, long-term studies in nature,” Peter Grant said. Without that, “we would not have detected or been able to interpret the immigration of an individual of one species and interbreeding with a member of the resident species.”

+

Although biologists do not yet know how much animal hybrid speciation occurs outside the Galápagos, they are becoming increasingly aware of hybrids as a powerful agent of evolution. “I think this paper really increases that signal,” Edwards said. “Researchers like me are going to be looking for it much more regularly.”

+
\ No newline at end of file diff --git a/html/result/url_content_a95dbd_.html b/html/result/url_content_a95dbd_.html new file mode 100644 index 00000000..a329e848 --- /dev/null +++ b/html/result/url_content_a95dbd_.html @@ -0,0 +1,147 @@ +
+ +

PLEASE NOTE THAT YOUR USE OF AND ACCESS TO OUR SERVICES (DEFINED BELOW) ARE SUBJECT TO THE FOLLOWING TERMS; IF YOU DO NOT AGREE TO ALL OF THE FOLLOWING, YOU MAY NOT USE OR ACCESS THE SERVICES IN ANY MANNER.

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Terms of Use

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Effective date: December 8, 2017

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Welcome to Kaggle. Please read on to learn the rules and restrictions that govern your use of our website(s), products, services and applications (the “Services”). If you have any questions, comments, or concerns regarding these terms or the Services, please contact us.

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These Terms of Use (the “Terms”) are a binding contract between you and Kaggle, Inc. (“Kaggle,” “we” and “us”). You must agree to and accept all of the Terms, or you don’t have the right to use the Services. Your use of the Services in any way means that you agree to all of these Terms, and these Terms will remain in effect while you use the Services. These Terms include the provisions in this document, as well as those in the Privacy Policy and Copyright Dispute Policy. In these Terms, the words “include” or “including” mean “including but not limited to”, and examples are for illustration purposes and are not limiting.

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We are constantly trying to improve our Services, so these Terms may need to change along with the Services. We reserve the right to change the Terms at any time, but if we do, we will bring it to your attention by placing a notice on the www.kaggle.com website, by sending you an email, or by some other means.  Changes will not apply retroactively and will become effective no sooner than 14 days after they are posted. However, changes addressing new functions for a Service or changes made for legal reasons will be effective immediately. If you don’t agree with the new Terms, you are free to reject them; unfortunately, that means you will no longer be able to use the Services. If you use the Services in any way after a change to the Terms is effective, that means you agree to all of the changes.

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Except for changes by us as described here, no other amendment or modification of these Terms will be effective unless in writing and signed by both you and us.

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The Children’s Online Privacy Protection Act (“COPPA”) requires that online service providers obtain parental consent before they knowingly collect personally identifiable information online from children who are under 13. We do not knowingly collect or solicit personally identifiable information from children under 13; if you are a child under 13, please do not attempt to register for the Services or send any personal information about yourself to us. If we learn we have collected personal information from a child under 13, we will delete that information as quickly as possible. If you believe that a child under 13 may have provided us personal information, please contact us at Kaggle Support.

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Subject to these Terms, a user may post (“Host User”) a skill-based competition or challenge on the Services (“Competition”) for other users to participate in such Competition (“Participant User”). Competitions are subject to separate Competition Rules (defined below) that are established by the Host User.  Competitions exclude games of chance, and you may not use or attempt to use the Service to host any such game of chance. Competitions are open to residents of the United States and worldwide, except if you are a resident of Crimea, Cuba, Iran, Syria, North Korea, Sudan, or any other place prohibited by law you may not enter any Competition but certain Competitions may also have further geographic restrictions and be open only to residents of certain countries.  If you would like to host a competition on Kaggle, go to https://www.kaggle.com/host. Competitions are run according to rules for participation, the data set(s) to be used by the Participant Users (“Datasets”), the criteria used by the Host User to select a winner of the Competition (the “Metric”), the prize awarded to such winner and when such prize will be awarded, and such rules and selection criteria must comply with all applicable laws and these Terms (collectively, “Competition Rules”).  Such Competition Rules will also include how and when a Participant User must submit Competition Entries (defined below) and the rights the Host User will be granted in such Competition Entry upon selecting such Competition Entry as the winner (“Winning Entry”) but the Host User will be granted rights in the Competition Entry only if the winner accepts payment of the prize. Certain rights granted in the Competition Entries and Winning Entries are described in Section 8 below.  The Competition Rules may impose additional restrictions or requirements for Competitions.

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The Host User must conspicuously display the Metric within the Competition Rules. The Host User must select an objective Metric and must apply that Metric impartially to each Team’s (defined below) selected entries. In selecting a winner, the Host User must apply the Metric and select the Participant Users with the best rankings based on the Metric.

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The Host User and each Participant User will comply with all Competition Rules. The Host User (including any user from Host User’s organization) may not compete in its hosted Competition nor cancel a Competition without first contacting us and receiving our consent to such cancellation. Any participation by a Host User (or any user from Host User’s organization) in its hosted Competitions is done so on an ineligible basis (e.g. they cannot receive a prize) and will not otherwise affect the selection of the Winning Entry.

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Subject to the Competition Rules, Participant Users may collaborate as a team as long as each such Participant User confirms its team membership through the Service and does not participate on more than one team for a specific Competition (“Team”). To be clear, you may not participate on more than one team per Competition. Subject to the Competition Rules, Teams may, however, merge with other Teams, but the merged Team will be responsible for all past entries by the component Teams. If your Team wins a Competition, the prize for winning will be distributed equally amongst the members of the winning Team, unless we receive identical requests for unequal prize splits from every member of the Team.

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You may be a Host User or a Participant User for a specific Competition (but not both!). A Competition creates a direct relationship between a Host User and a Participant User, and Kaggle will have no liability for any actions or content of a Host User or a Participant User. Kaggle may provide a Host User with a template for the Competition Rules, but such template is provided without any warranty whatsoever and the Host User is solely responsible for its Competition Rules. It is the sole responsibility of the Host User to ensure that the Competition Rules comply with applicable law.

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You acknowledge and agree that Kaggle may, at any time in its sole discretion and without any liability but without any obligation to do so, remove or disqualify a Participant User, a Host User or a Competition if Kaggle believes that such Participant User, Competition or Host User are in violation these Terms or otherwise pose a risk to Kaggle, the Service or another user of the Service.

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Regardless of anything to the contrary, Participant Users acknowledge and agree that Kaggle and Host Users have no obligation to hold a Competition Entry in confidence or otherwise restrict their activities based on receipt of such Competition Entry. Kaggle has no obligation to become involved in disputes between users (for example, between a Participant User and a Host User) or between users and any third party relating the use of the Services. Kaggle does not oversee Competitions (including the selection of Winning Entries) and does not endorse any content users submit to the Services. When you host or participate in a Competition, you release Kaggle from claims, damages, and demands of every kind — known or unknown, suspected or unsuspected, disclosed or undisclosed — arising out of or in any way related to such disputes and the Services. All content you access or submit via the Services is at your own risk. You are solely responsible for any resulting damage or loss to any party.

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Anything you post, upload, share, store, or otherwise provide through the Services is your “User Submission.” Some User Submissions are viewable by other users. To display your User Submissions on the Services, and to allow other users to enjoy them (where applicable), you grant us certain rights in those User Submissions. Please note that all of the following licenses are subject to our Privacy Policy to the extent they relate to User Submissions that are also your personally-identifiable information.

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For all User Submissions, you grant Kaggle a license to translate, modify (for technical purposes, for example making sure your content is viewable on an iPhone as well as a computer) and reproduce and otherwise act with respect to such User Submissions, in each case to enable us to operate the Services, as described in more detail below. You acknowledge and agree that Kaggle, in performing the required technical steps to provide the Services to our users (including you), may need to make changes to your User Submissions to conform and adapt those User Submissions to the technical requirements of communication networks, devices, services, or media, and the licenses you grant under these Terms include the rights to do so.  You also agree that all of the licenses you grant under these Terms are royalty-free, perpetual, irrevocable, and worldwide.  These are licenses only — your ownership in User Submissions is not affected.

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If you store a User Submission in your own personal Kaggle account, in a manner that is not viewable by any other user except you (a “Personal User Submission”), you grant Kaggle the license stated in the second paragraph of this Section 8, as well as a license to display, perform, and distribute your Personal User Submission for the sole purpose of making that Personal User Submission accessible to you and providing the Services necessary to do so.

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If you share a User Submission in a manner that only allows certain specified users to view it (for example, a private message to one or more other users) (a “Limited Audience User Submission”), then you grant Kaggle the license stated in the second paragraph of this Section 8, as well as a license to display, perform, and distribute your Limited Audience User Submission for the sole purpose of making that Limited Audience User Submission accessible to such other specified users, and providing the Services necessary to do so.. Also, you grant such other specified users a license to access that Limited Audience User Submission, and to use and exercise all rights in it, as permitted by the functionality of the Services.

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If you share a User Submission publicly on the Services and/or in a manner that allows more than just you or certain specified users to view it (such as a Dataset), or if you provide us (in a direct email or otherwise) with any feedback, suggestions, improvements, enhancements, and/or feature requests relating to the Services (each a “Public User Submission”), then you grant Kaggle the license stated in the second paragraph of this Section 8, as well as a license to display, perform, and distribute your Public User Submission for the purpose of making that Public User Submission accessible to all Kaggle users and providing the Services necessary to do so, as well as all other rights necessary to use and exercise all rights in that Public User Submission in connection with the Services for any purpose. Also, you grant all other users of the Services a license to access that Public User Submission, and to use and exercise all rights in it, as permitted by the functionality of the Services.

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If you are a Participant User and submit an entry to a Competition (“Competition Entry”), then you grant Kaggle the license stated in the second paragraph of this Section 8, as well as a license to display, perform, and distribute your Competition Entry for the purpose of making that Competition Entry accessible to the Host User, making that Competition Entry available to other Kaggle users as a Dataset, and providing the Services necessary to do so. Also, you grant such Host User a limited license to access and use the Competition Entry solely for the purposes of evaluating the Competition Entry under the Competition Rules. If you win a Competition, your Competition Entry for such Competition will be subject to further licensing as stated in the Competition Rules, but other than the limited licenses stated in these Terms, the intellectual property rights in your Competition Entries will not be transferred or licensed to the Competition Sponsor or Host User unless you accept the payment of the applicable prize stated in the applicable Competition Rules.

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If you and Kaggle agree (separate from these Terms) that Kaggle will assist you in setting up and managing your Competition, then in addition to the licenses stated above you also grant Kaggle a royalty-free, perpetual, irrevocable, and worldwide license to set up and manage your Competition, including your User Submissions for the Competition. Kaggle will have no liability regarding the applicable Competition, Content or User Submissions and the terms in Section 15 below will apply, except if you and Kaggle have executed a separate written agreement governing competitions or services ("Existing Agreement"), in which case the Existing Agreement will govern the Competition.

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You may have heard of the Digital Millennium Copyright Act (the “DMCA”), as it relates to online service providers, like Kaggle, being asked to remove material that allegedly violates someone’s copyright. We respect others’ intellectual property rights, and we reserve the right to delete or disable Content alleged to be infringing, and to terminate the accounts of repeat alleged infringers; to review our complete Copyright Dispute Policy and learn how to report potentially infringing content, click here Copyright Dispute Policy. To learn more about the DMCA, click here.

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We’re always trying to improve the Services, so they may change over time. We may suspend or discontinue any part of the Services, or we may introduce new features or impose limits on certain features or restrict access to parts or all of the Services. We’ll try to give you notice when we make a material change to the Services that would adversely affect you, but this isn’t always practical. Similarly, we reserve the right to remove any Content from the Services at any time, for any reason (including if someone alleges you contributed that Content in violation of these Terms), in our sole discretion, and without notice.

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The Kaggle Services may be free or we may charge a fee for using the Services. If you are using a free version of the Services, we will notify you before any Services you are then using begin carrying a fee, and if you wish to continue using such Services, you must pay all applicable fees for such Services.

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11.1. Paid Services. Certain of our Services may be subject to payments now or in the future (the “Paid Services”). Please see our Paid Services page for a description of the current Paid Services. Please note that any payment terms presented to you in the process of using or signing up for a Paid Service are deemed part of these Terms.

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11.2. Billing. We use a third-party payment processor (the “Payment Processor”) to bill you through a payment account linked to your Account on the Services (your “Billing Account”) for use of the Paid Services. The processing of payments will be subject to the terms, conditions and privacy policies of the Payment Processor in addition to these Terms. We are not responsible for errors by the Payment Processor. By choosing to use Paid Services, you agree to pay us, through the Payment Processor, all charges at the prices then in effect for any use of such Paid Services in accordance with the applicable payment terms and you authorize us, through the Payment Processor, to charge your chosen payment provider (your “Payment Method”). You agree to make payment using that selected Payment Method. We reserve the right to correct any errors or mistakes that it makes even if it has already requested or received payment.

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11.3. Payment Method. The terms of your payment will be based on your Payment Method and may be determined by agreements between you and the financial institution, credit card issuer or other provider of your chosen Payment Method. If we, through the Payment Processor, do not receive payment from you, you agree to pay all amounts due on your Billing Account upon demand.

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11.4. Recurring Billing. Some of the Paid Services may consist of an initial period, for which there is a one-time charge, followed by recurring period charges as agreed to by you. By choosing a recurring payment plan, you acknowledge that such Services have an initial and recurring payment feature and you accept responsibility for all recurring charges before cancellation. WE MAY SUBMIT PERIODIC CHARGES (E.G., MONTHLY) WITHOUT FURTHER AUTHORIZATION FROM YOU, UNTIL YOU PROVIDE PRIOR NOTICE (RECEIPT OF WHICH IS CONFIRMED BY US) THAT YOU HAVE TERMINATED THIS AUTHORIZATION OR WISH TO CHANGE YOUR PAYMENT METHOD. SUCH NOTICE WILL NOT AFFECT CHARGES SUBMITTED BEFORE WE REASONABLY COULD ACT. TO TERMINATE YOUR AUTHORIZATION OR CHANGE YOUR PAYMENT METHOD, GO HERE.

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11.5. Current Information Required. YOU MUST PROVIDE CURRENT, COMPLETE AND ACCURATE INFORMATION FOR YOUR BILLING ACCOUNT. YOU MUST PROMPTLY UPDATE ALL INFORMATION TO KEEP YOUR BILLING ACCOUNT CURRENT, COMPLETE AND ACCURATE (SUCH AS A CHANGE IN BILLING ADDRESS, CREDIT CARD NUMBER, OR CREDIT CARD EXPIRATION DATE), AND YOU MUST PROMPTLY NOTIFY US OR OUR PAYMENT PROCESSOR IF YOUR PAYMENT METHOD IS CANCELED (E.G., FOR LOSS OR THEFT) OR IF YOU BECOME AWARE OF A POTENTIAL BREACH OF SECURITY, SUCH AS THE UNAUTHORIZED DISCLOSURE OR USE OF YOUR USER NAME OR PASSWORD. CHANGES TO SUCH INFORMATION CAN BE MADE HERE. IF YOU FAIL TO PROVIDE ANY OF THE FOREGOING INFORMATION, YOU AGREE THAT WE MAY CONTINUE CHARGING YOU FOR ANY USE OF PAID SERVICES UNDER YOUR BILLING ACCOUNT UNLESS YOU HAVE TERMINATED YOUR PAID SERVICES AS STATED ABOVE.

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11.6. Change in Amount Authorized. If the amount to be charged to your Billing Account varies from the amount you preauthorized (other than due to the imposition or change in the amount of state sales taxes), you have the right to receive, and we will provide, notice of the amount to be charged and the date of the charge before the scheduled date of the transaction. Any agreement you have with your payment provider will govern your use of your Payment Method. You agree that we may accumulate charges incurred and submit them as one or more aggregate charges during or at the end of each billing cycle.

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11.7. Auto-Renewal for Subscription Services. Unless you opt out of auto-renewal, which can be done through your Account Settings, any Subscription Services you have signed up for will be automatically extended for successive renewal periods of the same duration as the subscription term originally selected, at the then-current non-promotional rate. To change or resign your Subscription Services at any time, go to Account Settings . If you terminate a Subscription Service, you may use your subscription until the end of your then-current term; your subscription will not be renewed after your then-current term expires. However, you won't be eligible for a prorated refund of any portion of the subscription fee paid for the then-current subscription period.

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11.8. Reaffirmation of Authorization. Your non-termination or continued use of a Paid Service reaffirms that we are authorized to charge your Payment Method for that Paid Service. We may submit those charges for payment and you will be responsible for such charges. This does not waive our right to seek payment directly from you. Your charges may be payable in advance, in arrears, per usage, or as otherwise described when you initially selected to use the Paid Service.

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These terms and conditions apply to Kaggle users who wish to post a job on the Kaggle Jobs Board.  The Kaggle Jobs Board is a Paid Service and your job posting is a User Submission and you are responsible for such User Submissions as stated in these Terms.  In addition, if you post a job on the Kaggle Jobs Board you agree to the following:

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You may only post jobs that relate to the fields of data science, data analytics, machine learning, or artificial intelligence.

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You represent, warrant, and agree that you will not submit any job posting that:

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a. does not comply with applicable local, national and international laws, including laws relating to labor and employment, equal employment opportunity and employment eligibility requirements, data privacy, data access and use, and intellectual property;

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b. is for a job located in countries subject to economic sanctions of the United States government; or

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c. contains inaccurate, false, or misleading information.

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\ No newline at end of file diff --git a/main.py b/main.py index d601c429..2905a37d 100644 --- a/main.py +++ b/main.py @@ -14,7 +14,7 @@ def parse_summary(filename=None,url=None): html = f.read() n = "content_%s"%os.path.basename(filename) if url: - html = request.get(url) + html = requests.get(url).text n = "url_content_%s_.html"%hashlib.md5(url.encode("utf-8")).hexdigest()[0:6] doc = Document(html) summary = doc.summary() diff --git a/tmp.py b/tmp.py new file mode 100644 index 00000000..5c5750a4 --- /dev/null +++ b/tmp.py @@ -0,0 +1,23 @@ +import re + + + +bad_attrs = ['width', 'height', 'style', '[-a-z]*color', 'background[-a-z]*', 'on*'] +single_quoted = "'[^']+'" +double_quoted = '"[^"]+"' +non_space = '[^ "\'>]+' +h = re.compile("<" # open + "([^>]+) " # prefix + "(?:%s) *" % ('|'.join(bad_attrs),) + # undesirable attributes + '= *(?:%s|%s|%s)' % (non_space, single_quoted, double_quoted) + # value + "([^>]*)" # postfix + ">" # end +, re.I) + + +if __name__ == "__main__": + html = "" + r = h.sub("acv",html) + print(r) + p = re.compile("\d") + print(p.sub("d","aaa3aaa4aaa543aaa4"))