A team of scientists has discovered the youngest dinosaur preserved in the fossil record before the catastrophic meteor impact 65 million years ago. The finding indicates that dinosaurs did not go extinct prior to the impact and provides further evidence as to whether the impact was in fact the cause of their extinction.
Researchers from Yale University discovered the fossilized horn of a ceratopsian – likely a Triceratops, which are common to the area – in the Hell Creek formation in Montana last year. They found the fossil buried just five inches below the K-T boundary, the geological layer that marks the transition from the Cretaceous period to the Tertiary period at the time of the mass extinction that took place 65 million years ago.
Since the impact hypothesis for the demise of the dinosaurs was first proposed more than 30 years ago, many scientists have come to believe the meteor caused the mass extinction and wiped out the dinosaurs, but a sticking point has been an apparent lack of fossils buried within the 10 feet of rock below the K-T boundary. The seeming anomaly has come to be known as the "three-meter gap." Until now, this gap has caused some paleontologists to question whether the non-avian dinosaurs of the era – which included Tyrannosaurus rex, Triceratops, Torosaurus and the duckbilled dinosaurs – gradually went extinct sometime before the meteor struck. (Avian dinosaurs survived the impact, and eventually gave rise to modern-day birds.)
"This discovery suggests the three-meter gap doesn't exist," said Yale graduate student Tyler Lyson, director of the Marmarth Research Foundation and lead author of the study, published online July 12 in the journal Biology Letters. "The fact that this specimen was so close to the boundary indicates that at least some dinosaurs were doing fine right up until the impact."
While the team can't determine the exact age of the dinosaur, Lyson said it likely lived tens of thousands to just a few thousand years before the impact. "This discovery provides some evidence that dinosaurs didn't slowly die out before the meteor struck," he said.
Eric Sargis, curator of vertebrate paleontology at the Yale Peabody Museum of Natural History, and graduate student Stephen Chester discovered the ceratopsian last year while searching for fossilized mammals that evolved after the meteor impact. At first, Lyson said, the team thought it was buried within about three feet of the K-T boundary, but were surprised to learn just how close to the boundary – and hence, how close in time to the impact – it was. They sent soil samples to a laboratory to determine the exact location of the boundary, which is marked by the relative abundance of certain types of fossilized pollen and other geological indicators but is difficult to determine visually while in the field.
Because the dinosaur was buried in a mudstone floodplain, the team knew it hadn't been re-deposited from older sediments, which can sometimes happen when fossils are found in riverbeds that may have eroded and re-distributed material over time.
The team is now examining other fossil specimens that appear to be buried close to the K-T boundary and expect to find more, Lyson said. He suspects that other fossils discovered in the past may have been closer to the boundary than originally thought and that the so-called three-meter gap never existed.
"We should be able to verify that using the more sophisticated soil analysis technique rather than estimating the boundary's location based solely on a visual examination of the rock formations while in the field, which is what has typically been done in the past," Lyson said.
http://archaeologynewsnetwork.blogspot.com/2011/07/last-dinosaur-before-mass-extinction.html
Showing posts with label mass extinction. Show all posts
Showing posts with label mass extinction. Show all posts
Friday, July 15, 2011
Wednesday, March 2, 2011
Humans causing mass extinction of Earth's species
March 2, 2011
The good news is that so far, a study finds, the total loss is not devastating
(Livescience.com)
Are humans causing a mass extinction on the magnitude of the one that killed the dinosaurs?
The answer is yes, according to a new analysis -- but we still have some time to stop it.
Mass extinctions include events in which 75 percent of the species on Earth disappear within a geologically short time period, usually on the order of a few hundred thousand to a couple million years. It's happened only five times before in the past 540 million years of multicellular life on Earth. (The last great extinction occurred 65 million years ago, when the dinosaurs were wiped out.) At current rates of extinction, the study found, Earth will enter its sixth mass extinction within the next 300 to 2,000 years.
"It's bittersweet, because we're showing that we have this crisis," study co-author Elizabeth Ferrer, a graduate student in biology at the University of California, Berkeley, told LiveScience. "But we still have time to fix this."
Others aren't so optimistic that humans will actually do anything to stop the looming disaster, saying that politics is successfully working against saving species and the planet.
The 6th extinction
>Species go extinct all the time, said Anthony Barnosky, the curator of the Museum of Paleontology at UC Berkeley and another co-author of the paper, which appears in today's (March 2) issue of the journal Nature. But new species also evolve constantly, meaning that biodiversity usually stays constant. Mass extinctions happen when that balance goes out of whack. Suddenly, extinctions far outpace the genesis of new species, and the old rules for species survival go out the window.
"If the fossil record tells us one thing, it's that when we kick over into a mass extinction regime, results are extreme, they're irreversible and they're unpredictable," David Jablonski, a paleontologist at the University of Chicago who was not involved in the study, told LiveScience. "Factors that promote success and survival during normal times seem to melt away."
Everyone knows that we now lose many species a year, Barnosky said. "The question is, 'Is the pace of extinction we're seeing today over these short time intervals usual or unusual?'"
Answering the question requires stitching together two types of data: that from the fossil record and that collected by conservation biologists in the modern era. They don't always match up well. For example, Barnosky said, fossils tell us lots about the history of clams, snails and other invertebrates. But in the modern world, biologists have only assessed the extinction risk for 3 percent of known species of such invertebrates. That makes comparisons tough.
The fossil record also presents a blurrier history than today's yearly records of species counts. Sparse examples of a species may be distributed across millions of years of fossil history, the researchers wrote, while modern surveys provide dense samples over short periods of time. And even the best source of modern data -- the International Union for the Conservation of Nature Red List of threatened and endangered species -- has cataloged the conservation status of less than 2.7 percent of the 1.9 million named species out there.
Coming crisis
The researchers worked to combine these two sources of data, Ferrer said, taking a conservative approach to filling in gaps and estimating future directions. They found that the overall rate of extinction is, in fact, between three to 80 times higher than non-mass extinction rates. Most likely, species are going extinct three to 12 times faster than would be expected if there were no crisis, Ferrer said.
That gives Earth between three and 22 centuries to reach the point of mass extinction if nothing is done to stop the problem. (The wide range is a factor of the uncertainty in the data and different rates of extinction found in various species.) The good news, Barnosky said, is that the total loss so far is not devastating. In the last 200 years, the researchers found, only 1 to 2 percent of all species have gone extinct.
The strongest evidence for comparison between modern and ancient times comes from vertebrate animals, Barnosky said, which means there is still work to do collecting better data for more robust comparisons with better invertebrate data. But, he said, the research "shows absolutely without a doubt that we do have this major problem."
Back from the brink?
The culprits for the biodiversity loss include climate change, habitat loss, pollution and overfishing, the researchers wrote.
"Most of the mechanisms that are occurring today, most of them are caused by us," Ferrer said.
So can we fix it? Yes, there's time to cut dependence on fossil fuels, alleviate climate change and commit to conservation of habitat, the study scientists say. The more pressing question is, will we?
Barnosky and Ferrer both say they're optimistic that people will pull together to solve the problem once they understand the magnitude of the looming disaster. Jablonski puts himself into the "guardedly optimistic category."
"I think a lot of the problems probably have a lot more to do with politics than with science," Jablonski said.
That's where Paul Ehrlich, the president of the Center for Conservation Biology at Stanford University and author of "The Population Bomb" (Sierra Club-Ballantine, 1968), sees little hope.
"Everything we're doing in Washington [D.C.] today is working in the wrong direction," Ehrlich, who was not involved in the research, told LiveScience. "There isn't a single powerful person in the world who is really talking about what the situation is ... It's hard to be cheery when you don't see the slightest sign of any real attention being paid."
Other researchers take an upbeat view.
"If we have a business-as-usual scenario, it is pretty grim, but it isn't yet written," Stuart Pimm, a professor of conservation ecology at Duke University who was not involved in the research, told LiveScience in a phone interview from Chile, where he was doing fieldwork.
In 2010, Pimm said, the United Nations declared the International Year of Biodiversity. According to a UN statement, the 193 countries involved agreed to protect 17 percent of Earth's terrestrial ecosystems and 10 percent of marine and coastal areas. Some types of ecosystems still lag behind, Pimm said, but there is reason for hope.
"I hope that this will alert people to the fact that we are living in geologically unprecedented times," Pimm said. "Only five times in Earth's history has life been as threatened as it is now."
http://www.cbsnews.com/stories/2011/03/02/scitech/main20038438.shtml
The good news is that so far, a study finds, the total loss is not devastating
(Livescience.com)
Are humans causing a mass extinction on the magnitude of the one that killed the dinosaurs?
The answer is yes, according to a new analysis -- but we still have some time to stop it.
Mass extinctions include events in which 75 percent of the species on Earth disappear within a geologically short time period, usually on the order of a few hundred thousand to a couple million years. It's happened only five times before in the past 540 million years of multicellular life on Earth. (The last great extinction occurred 65 million years ago, when the dinosaurs were wiped out.) At current rates of extinction, the study found, Earth will enter its sixth mass extinction within the next 300 to 2,000 years.
"It's bittersweet, because we're showing that we have this crisis," study co-author Elizabeth Ferrer, a graduate student in biology at the University of California, Berkeley, told LiveScience. "But we still have time to fix this."
Others aren't so optimistic that humans will actually do anything to stop the looming disaster, saying that politics is successfully working against saving species and the planet.
The 6th extinction
>Species go extinct all the time, said Anthony Barnosky, the curator of the Museum of Paleontology at UC Berkeley and another co-author of the paper, which appears in today's (March 2) issue of the journal Nature. But new species also evolve constantly, meaning that biodiversity usually stays constant. Mass extinctions happen when that balance goes out of whack. Suddenly, extinctions far outpace the genesis of new species, and the old rules for species survival go out the window.
"If the fossil record tells us one thing, it's that when we kick over into a mass extinction regime, results are extreme, they're irreversible and they're unpredictable," David Jablonski, a paleontologist at the University of Chicago who was not involved in the study, told LiveScience. "Factors that promote success and survival during normal times seem to melt away."
Everyone knows that we now lose many species a year, Barnosky said. "The question is, 'Is the pace of extinction we're seeing today over these short time intervals usual or unusual?'"
Answering the question requires stitching together two types of data: that from the fossil record and that collected by conservation biologists in the modern era. They don't always match up well. For example, Barnosky said, fossils tell us lots about the history of clams, snails and other invertebrates. But in the modern world, biologists have only assessed the extinction risk for 3 percent of known species of such invertebrates. That makes comparisons tough.
The fossil record also presents a blurrier history than today's yearly records of species counts. Sparse examples of a species may be distributed across millions of years of fossil history, the researchers wrote, while modern surveys provide dense samples over short periods of time. And even the best source of modern data -- the International Union for the Conservation of Nature Red List of threatened and endangered species -- has cataloged the conservation status of less than 2.7 percent of the 1.9 million named species out there.
Coming crisis
The researchers worked to combine these two sources of data, Ferrer said, taking a conservative approach to filling in gaps and estimating future directions. They found that the overall rate of extinction is, in fact, between three to 80 times higher than non-mass extinction rates. Most likely, species are going extinct three to 12 times faster than would be expected if there were no crisis, Ferrer said.
That gives Earth between three and 22 centuries to reach the point of mass extinction if nothing is done to stop the problem. (The wide range is a factor of the uncertainty in the data and different rates of extinction found in various species.) The good news, Barnosky said, is that the total loss so far is not devastating. In the last 200 years, the researchers found, only 1 to 2 percent of all species have gone extinct.
The strongest evidence for comparison between modern and ancient times comes from vertebrate animals, Barnosky said, which means there is still work to do collecting better data for more robust comparisons with better invertebrate data. But, he said, the research "shows absolutely without a doubt that we do have this major problem."
Back from the brink?
The culprits for the biodiversity loss include climate change, habitat loss, pollution and overfishing, the researchers wrote.
"Most of the mechanisms that are occurring today, most of them are caused by us," Ferrer said.
So can we fix it? Yes, there's time to cut dependence on fossil fuels, alleviate climate change and commit to conservation of habitat, the study scientists say. The more pressing question is, will we?
Barnosky and Ferrer both say they're optimistic that people will pull together to solve the problem once they understand the magnitude of the looming disaster. Jablonski puts himself into the "guardedly optimistic category."
"I think a lot of the problems probably have a lot more to do with politics than with science," Jablonski said.
That's where Paul Ehrlich, the president of the Center for Conservation Biology at Stanford University and author of "The Population Bomb" (Sierra Club-Ballantine, 1968), sees little hope.
"Everything we're doing in Washington [D.C.] today is working in the wrong direction," Ehrlich, who was not involved in the research, told LiveScience. "There isn't a single powerful person in the world who is really talking about what the situation is ... It's hard to be cheery when you don't see the slightest sign of any real attention being paid."
Other researchers take an upbeat view.
"If we have a business-as-usual scenario, it is pretty grim, but it isn't yet written," Stuart Pimm, a professor of conservation ecology at Duke University who was not involved in the research, told LiveScience in a phone interview from Chile, where he was doing fieldwork.
In 2010, Pimm said, the United Nations declared the International Year of Biodiversity. According to a UN statement, the 193 countries involved agreed to protect 17 percent of Earth's terrestrial ecosystems and 10 percent of marine and coastal areas. Some types of ecosystems still lag behind, Pimm said, but there is reason for hope.
"I hope that this will alert people to the fact that we are living in geologically unprecedented times," Pimm said. "Only five times in Earth's history has life been as threatened as it is now."
http://www.cbsnews.com/stories/2011/03/02/scitech/main20038438.shtml
Sunday, January 2, 2011
Man could create new mass extinction
Mankind's introduction of invasive species across the globe and destruction of natural habitats threatens to destroy the diversity of species essential to the natural world, researchers claim.
The modern biodiversity crisis, a lack of variation in life forms, means Earth could meet a similar fate to the collapse of marine life 378-375 million years ago – and that of the dinosaurs.
Although Earth has experienced five major mass extinction events, the environmental crash during this Late Devonian event was unlike any other in the planet's history.
The actual number of extinctions was not higher than the natural rate of species loss, but very few new species arose leading to an overall loss of life.
Dr Alycia Stigall, a scientist at Ohio University and author of the paper said: "We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis.
The main mode of speciation that occurs in the geological record is shut down during the Devonian. It just stops in its tracks."
Lisa Boush, programme director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research, said: "This research significantly contributes to our understanding of species invasions from a deep-time perspective.
"The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth.
"It provides and important perspective on our current biodiversity crisis."
The research suggests that the typical method by which new species originate, or vicariance, was absent during this ancient phase of Earth's history and could be to blame for the mass extinction.
Vicariance occurs when a population becomes geographically divided by a natural, long-term event, such as the formation of a mountain range or a new river channel and evolves into a different species.
New species can also originate through dispersal, which occurs when a subset of a population moves to a new location.
Dr Stigall said that human activity has now introduced a high number of invasive species into new ecosystems, making this study relevant for the current biodiversity crisis.
In addition, the modern extinction rate exceeds the rate of ancient extinction events such as the dinosaurs.
Dr Stigall said: "Even if you can stop habitat loss, the fact that we've moved all these invasive species around the planet will take a long time to recover from because the high level of invasions has suppressed the speciation rate substantially."
She suggests that maintaining Earth's ecosystems would be helped by focusing efforts and resources on the protection of a new species generation.
She said: "The more we know about this process, the more we will understand how to best preserve biodiversity."
The research results are published in the journal PLoS One.
http://www.telegraph.co.uk/wirecopy/8234135/Man-could-create-new-mass-extinction.html
The modern biodiversity crisis, a lack of variation in life forms, means Earth could meet a similar fate to the collapse of marine life 378-375 million years ago – and that of the dinosaurs.
Although Earth has experienced five major mass extinction events, the environmental crash during this Late Devonian event was unlike any other in the planet's history.
The actual number of extinctions was not higher than the natural rate of species loss, but very few new species arose leading to an overall loss of life.
Dr Alycia Stigall, a scientist at Ohio University and author of the paper said: "We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis.
The main mode of speciation that occurs in the geological record is shut down during the Devonian. It just stops in its tracks."
Lisa Boush, programme director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research, said: "This research significantly contributes to our understanding of species invasions from a deep-time perspective.
"The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth.
"It provides and important perspective on our current biodiversity crisis."
The research suggests that the typical method by which new species originate, or vicariance, was absent during this ancient phase of Earth's history and could be to blame for the mass extinction.
Vicariance occurs when a population becomes geographically divided by a natural, long-term event, such as the formation of a mountain range or a new river channel and evolves into a different species.
New species can also originate through dispersal, which occurs when a subset of a population moves to a new location.
Dr Stigall said that human activity has now introduced a high number of invasive species into new ecosystems, making this study relevant for the current biodiversity crisis.
In addition, the modern extinction rate exceeds the rate of ancient extinction events such as the dinosaurs.
Dr Stigall said: "Even if you can stop habitat loss, the fact that we've moved all these invasive species around the planet will take a long time to recover from because the high level of invasions has suppressed the speciation rate substantially."
She suggests that maintaining Earth's ecosystems would be helped by focusing efforts and resources on the protection of a new species generation.
She said: "The more we know about this process, the more we will understand how to best preserve biodiversity."
The research results are published in the journal PLoS One.
http://www.telegraph.co.uk/wirecopy/8234135/Man-could-create-new-mass-extinction.html
Man could create new mass extinction
Mankind's introduction of invasive species across the globe and destruction of natural habitats threatens to destroy the diversity of species essential to the natural world, researchers claim.
The modern biodiversity crisis, a lack of variation in life forms, means Earth could meet a similar fate to the collapse of marine life 378-375 million years ago – and that of the dinosaurs.
Although Earth has experienced five major mass extinction events, the environmental crash during this Late Devonian event was unlike any other in the planet's history.
The actual number of extinctions was not higher than the natural rate of species loss, but very few new species arose leading to an overall loss of life.
Dr Alycia Stigall, a scientist at Ohio University and author of the paper said: "We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis.
The main mode of speciation that occurs in the geological record is shut down during the Devonian. It just stops in its tracks."
Lisa Boush, programme director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research, said: "This research significantly contributes to our understanding of species invasions from a deep-time perspective.
"The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth.
"It provides and important perspective on our current biodiversity crisis."
The research suggests that the typical method by which new species originate, or vicariance, was absent during this ancient phase of Earth's history and could be to blame for the mass extinction.
Vicariance occurs when a population becomes geographically divided by a natural, long-term event, such as the formation of a mountain range or a new river channel and evolves into a different species.
New species can also originate through dispersal, which occurs when a subset of a population moves to a new location.
Dr Stigall said that human activity has now introduced a high number of invasive species into new ecosystems, making this study relevant for the current biodiversity crisis.
In addition, the modern extinction rate exceeds the rate of ancient extinction events such as the dinosaurs.
Dr Stigall said: "Even if you can stop habitat loss, the fact that we've moved all these invasive species around the planet will take a long time to recover from because the high level of invasions has suppressed the speciation rate substantially."
She suggests that maintaining Earth's ecosystems would be helped by focusing efforts and resources on the protection of a new species generation.
She said: "The more we know about this process, the more we will understand how to best preserve biodiversity."
The research results are published in the journal PLoS One.
http://www.telegraph.co.uk/wirecopy/8234135/Man-could-create-new-mass-extinction.html
The modern biodiversity crisis, a lack of variation in life forms, means Earth could meet a similar fate to the collapse of marine life 378-375 million years ago – and that of the dinosaurs.
Although Earth has experienced five major mass extinction events, the environmental crash during this Late Devonian event was unlike any other in the planet's history.
The actual number of extinctions was not higher than the natural rate of species loss, but very few new species arose leading to an overall loss of life.
Dr Alycia Stigall, a scientist at Ohio University and author of the paper said: "We refer to the Late Devonian as a mass extinction, but it was actually a biodiversity crisis.
The main mode of speciation that occurs in the geological record is shut down during the Devonian. It just stops in its tracks."
Lisa Boush, programme director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research, said: "This research significantly contributes to our understanding of species invasions from a deep-time perspective.
"The knowledge is critical to determining the cause and extent of mass extinctions through time, especially the five biggest biodiversity crises in the history of life on Earth.
"It provides and important perspective on our current biodiversity crisis."
The research suggests that the typical method by which new species originate, or vicariance, was absent during this ancient phase of Earth's history and could be to blame for the mass extinction.
Vicariance occurs when a population becomes geographically divided by a natural, long-term event, such as the formation of a mountain range or a new river channel and evolves into a different species.
New species can also originate through dispersal, which occurs when a subset of a population moves to a new location.
Dr Stigall said that human activity has now introduced a high number of invasive species into new ecosystems, making this study relevant for the current biodiversity crisis.
In addition, the modern extinction rate exceeds the rate of ancient extinction events such as the dinosaurs.
Dr Stigall said: "Even if you can stop habitat loss, the fact that we've moved all these invasive species around the planet will take a long time to recover from because the high level of invasions has suppressed the speciation rate substantially."
She suggests that maintaining Earth's ecosystems would be helped by focusing efforts and resources on the protection of a new species generation.
She said: "The more we know about this process, the more we will understand how to best preserve biodiversity."
The research results are published in the journal PLoS One.
http://www.telegraph.co.uk/wirecopy/8234135/Man-could-create-new-mass-extinction.html
Friday, November 19, 2010
Haiti on brink of mass extinctions
Frogs are nature's early warning system
November 2010: Haiti is on the brink of an era of mass extinctions similar to the time when dinosaurs and many other species suddenly disappeared from the Earth, a leading biologist is warning.
Announcing the at the establishment of a rescue programme for Haiti's threatened frogs and other species, including captive-breeding and gene-preservation efforts, Blair Hedges, Professor of Biology at Penn State University said: ‘During the next few decades, many Haitian species of plants and animals will become extinct because the forests where they live, which originally covered the entire country, are nearly gone.
‘Frogs are especially vulnerable, so their decline is a biological early-warning signal of a dangerously deteriorating environment, just as a dying canary is an early-warning sign of dangerously deteriorating air in a coal mine,' added Hedges, who is also one of the world's foremost authorities on amphibians and reptiles. ‘When frogs start disappearing, other species will follow and the Haitian people will suffer, as well, from this environmental catastrophe.'
One species already breeding in captivity
Hedges recently relocated ten critically endangered species of frogs from Haiti to a captive-breeding programme at Philadelphia Zoo. One of these species already has begun breeding, laying eggs, and producing hatchlings. Hedges has discovered at least five new frog species during three expeditions to Haiti this year, but he was not able to find two species that may now be extinct because they have not been seen there for 25 years. His scientific descriptions of the new species will be published in future issues of research journals.
The rescue mission led by Hedges is part of a new effort supported by the National Science Foundation to determine which species of amphibians and reptiles currently survive in Haiti, to pinpoint their locations, to discover any new species that previously were not documented scientifically, to relocate live populations of frogs for captive breeding, and to deep-freeze cells at Penn State.
Deep freezing some frogs in case they die out in Haiti
‘Captive breeding and cryobanking are two efforts to preserve the species in case they become extinct in Haiti,' said Hedges, who is one of the few scientists worldwide who have established cryobanking programmes in their labs for endangered frogs and other species.
Cryobanking involves the preservation of cells and DNA in liquid nitrogen that will permit whole-animal cloning, if necessary, in the future. ‘These are time-consuming and costly backup plans to save species, normally reserved for those species closest to extinction,' Hedges said. ‘The goal is to release offspring of rescued frogs in Haiti if and when their forest habitat improves.'
Hedges and the Philadelphia Zoo also are working with the Haitian government and non-governmental agencies to train Haitians in this conservation research so that they can develop the capacity to breed these species in Haiti.
Third of world's frogs face extinction - but 92 per cent of Haiti's frogs are threatened
Frog species have been disappearing worldwide during the past ten to 20 years, and one-third of the Earth's 6,000 frog species are now threatened with extinction. But in Haiti, 92 per cent of Haiti's 50 frog species are threatened - the highest percentage of any country in the world.
‘We found that as many as 26 species occur together in the isolated mountain forests of southwest Haiti,' said Hedges, ‘greatly increasing the threat of mass extinctions when the forests there are cut down.' Of the 50 frog species in Haiti, two-thirds - 30 species - live only in Haiti and do not occur in the neighboring Dominican Republic.
Haiti's lush forests have become a lunar landscape
‘Less than one per cent of the original forest is left in Haiti, which is a lower percentage than in any other country that I know of,' Hedges added. ‘There definitely is no other place in the western half of the world - and some scientists would argue in the entire world - where the extinction threat is greater than in Haiti."
Hedges explained that the forests of Haiti are disappearing because the trees were being cut down to produce charcoal for the 10-million Haitian people who have few other sources of cooking fuel.
‘Forests from some entire mountains now have been removed completely. In places,' said Hedges. ‘It looks like a lunar landscape, with nearly all the soil washed away and only the rocks and some weeds left behind."
‘The pressure for cutting down the forests is coming from a whole island nation of people needing cooking fuel - a problem requiring economic and possibly engineering solutions and needing the help of major international conservation organisations and government agencies,' said Philippe Bayard, President of the Audubon Society of Haiti and collaborator with Hedges in efforts to save Haiti's biodiversity. ‘Unless effective help arrives soon, it is inevitable that there will be mass extinctions, and I think they are in progress.'
http://www.wildlifeextra.com/go/news/haiti-extinction.html
November 2010: Haiti is on the brink of an era of mass extinctions similar to the time when dinosaurs and many other species suddenly disappeared from the Earth, a leading biologist is warning.
Announcing the at the establishment of a rescue programme for Haiti's threatened frogs and other species, including captive-breeding and gene-preservation efforts, Blair Hedges, Professor of Biology at Penn State University said: ‘During the next few decades, many Haitian species of plants and animals will become extinct because the forests where they live, which originally covered the entire country, are nearly gone.
‘Frogs are especially vulnerable, so their decline is a biological early-warning signal of a dangerously deteriorating environment, just as a dying canary is an early-warning sign of dangerously deteriorating air in a coal mine,' added Hedges, who is also one of the world's foremost authorities on amphibians and reptiles. ‘When frogs start disappearing, other species will follow and the Haitian people will suffer, as well, from this environmental catastrophe.'
One species already breeding in captivity
Hedges recently relocated ten critically endangered species of frogs from Haiti to a captive-breeding programme at Philadelphia Zoo. One of these species already has begun breeding, laying eggs, and producing hatchlings. Hedges has discovered at least five new frog species during three expeditions to Haiti this year, but he was not able to find two species that may now be extinct because they have not been seen there for 25 years. His scientific descriptions of the new species will be published in future issues of research journals.
The rescue mission led by Hedges is part of a new effort supported by the National Science Foundation to determine which species of amphibians and reptiles currently survive in Haiti, to pinpoint their locations, to discover any new species that previously were not documented scientifically, to relocate live populations of frogs for captive breeding, and to deep-freeze cells at Penn State.
Deep freezing some frogs in case they die out in Haiti
‘Captive breeding and cryobanking are two efforts to preserve the species in case they become extinct in Haiti,' said Hedges, who is one of the few scientists worldwide who have established cryobanking programmes in their labs for endangered frogs and other species.
Cryobanking involves the preservation of cells and DNA in liquid nitrogen that will permit whole-animal cloning, if necessary, in the future. ‘These are time-consuming and costly backup plans to save species, normally reserved for those species closest to extinction,' Hedges said. ‘The goal is to release offspring of rescued frogs in Haiti if and when their forest habitat improves.'
Hedges and the Philadelphia Zoo also are working with the Haitian government and non-governmental agencies to train Haitians in this conservation research so that they can develop the capacity to breed these species in Haiti.
Third of world's frogs face extinction - but 92 per cent of Haiti's frogs are threatened
Frog species have been disappearing worldwide during the past ten to 20 years, and one-third of the Earth's 6,000 frog species are now threatened with extinction. But in Haiti, 92 per cent of Haiti's 50 frog species are threatened - the highest percentage of any country in the world.
‘We found that as many as 26 species occur together in the isolated mountain forests of southwest Haiti,' said Hedges, ‘greatly increasing the threat of mass extinctions when the forests there are cut down.' Of the 50 frog species in Haiti, two-thirds - 30 species - live only in Haiti and do not occur in the neighboring Dominican Republic.
Haiti's lush forests have become a lunar landscape
‘Less than one per cent of the original forest is left in Haiti, which is a lower percentage than in any other country that I know of,' Hedges added. ‘There definitely is no other place in the western half of the world - and some scientists would argue in the entire world - where the extinction threat is greater than in Haiti."
Hedges explained that the forests of Haiti are disappearing because the trees were being cut down to produce charcoal for the 10-million Haitian people who have few other sources of cooking fuel.
‘Forests from some entire mountains now have been removed completely. In places,' said Hedges. ‘It looks like a lunar landscape, with nearly all the soil washed away and only the rocks and some weeds left behind."
‘The pressure for cutting down the forests is coming from a whole island nation of people needing cooking fuel - a problem requiring economic and possibly engineering solutions and needing the help of major international conservation organisations and government agencies,' said Philippe Bayard, President of the Audubon Society of Haiti and collaborator with Hedges in efforts to save Haiti's biodiversity. ‘Unless effective help arrives soon, it is inevitable that there will be mass extinctions, and I think they are in progress.'
http://www.wildlifeextra.com/go/news/haiti-extinction.html
Haiti on brink of mass extinctions
Frogs are nature's early warning system
November 2010: Haiti is on the brink of an era of mass extinctions similar to the time when dinosaurs and many other species suddenly disappeared from the Earth, a leading biologist is warning.
Announcing the at the establishment of a rescue programme for Haiti's threatened frogs and other species, including captive-breeding and gene-preservation efforts, Blair Hedges, Professor of Biology at Penn State University said: ‘During the next few decades, many Haitian species of plants and animals will become extinct because the forests where they live, which originally covered the entire country, are nearly gone.
‘Frogs are especially vulnerable, so their decline is a biological early-warning signal of a dangerously deteriorating environment, just as a dying canary is an early-warning sign of dangerously deteriorating air in a coal mine,' added Hedges, who is also one of the world's foremost authorities on amphibians and reptiles. ‘When frogs start disappearing, other species will follow and the Haitian people will suffer, as well, from this environmental catastrophe.'
One species already breeding in captivity
Hedges recently relocated ten critically endangered species of frogs from Haiti to a captive-breeding programme at Philadelphia Zoo. One of these species already has begun breeding, laying eggs, and producing hatchlings. Hedges has discovered at least five new frog species during three expeditions to Haiti this year, but he was not able to find two species that may now be extinct because they have not been seen there for 25 years. His scientific descriptions of the new species will be published in future issues of research journals.
The rescue mission led by Hedges is part of a new effort supported by the National Science Foundation to determine which species of amphibians and reptiles currently survive in Haiti, to pinpoint their locations, to discover any new species that previously were not documented scientifically, to relocate live populations of frogs for captive breeding, and to deep-freeze cells at Penn State.
Deep freezing some frogs in case they die out in Haiti
‘Captive breeding and cryobanking are two efforts to preserve the species in case they become extinct in Haiti,' said Hedges, who is one of the few scientists worldwide who have established cryobanking programmes in their labs for endangered frogs and other species.
Cryobanking involves the preservation of cells and DNA in liquid nitrogen that will permit whole-animal cloning, if necessary, in the future. ‘These are time-consuming and costly backup plans to save species, normally reserved for those species closest to extinction,' Hedges said. ‘The goal is to release offspring of rescued frogs in Haiti if and when their forest habitat improves.'
Hedges and the Philadelphia Zoo also are working with the Haitian government and non-governmental agencies to train Haitians in this conservation research so that they can develop the capacity to breed these species in Haiti.
Third of world's frogs face extinction - but 92 per cent of Haiti's frogs are threatened
Frog species have been disappearing worldwide during the past ten to 20 years, and one-third of the Earth's 6,000 frog species are now threatened with extinction. But in Haiti, 92 per cent of Haiti's 50 frog species are threatened - the highest percentage of any country in the world.
‘We found that as many as 26 species occur together in the isolated mountain forests of southwest Haiti,' said Hedges, ‘greatly increasing the threat of mass extinctions when the forests there are cut down.' Of the 50 frog species in Haiti, two-thirds - 30 species - live only in Haiti and do not occur in the neighboring Dominican Republic.
Haiti's lush forests have become a lunar landscape
‘Less than one per cent of the original forest is left in Haiti, which is a lower percentage than in any other country that I know of,' Hedges added. ‘There definitely is no other place in the western half of the world - and some scientists would argue in the entire world - where the extinction threat is greater than in Haiti."
Hedges explained that the forests of Haiti are disappearing because the trees were being cut down to produce charcoal for the 10-million Haitian people who have few other sources of cooking fuel.
‘Forests from some entire mountains now have been removed completely. In places,' said Hedges. ‘It looks like a lunar landscape, with nearly all the soil washed away and only the rocks and some weeds left behind."
‘The pressure for cutting down the forests is coming from a whole island nation of people needing cooking fuel - a problem requiring economic and possibly engineering solutions and needing the help of major international conservation organisations and government agencies,' said Philippe Bayard, President of the Audubon Society of Haiti and collaborator with Hedges in efforts to save Haiti's biodiversity. ‘Unless effective help arrives soon, it is inevitable that there will be mass extinctions, and I think they are in progress.'
http://www.wildlifeextra.com/go/news/haiti-extinction.html
November 2010: Haiti is on the brink of an era of mass extinctions similar to the time when dinosaurs and many other species suddenly disappeared from the Earth, a leading biologist is warning.
Announcing the at the establishment of a rescue programme for Haiti's threatened frogs and other species, including captive-breeding and gene-preservation efforts, Blair Hedges, Professor of Biology at Penn State University said: ‘During the next few decades, many Haitian species of plants and animals will become extinct because the forests where they live, which originally covered the entire country, are nearly gone.
‘Frogs are especially vulnerable, so their decline is a biological early-warning signal of a dangerously deteriorating environment, just as a dying canary is an early-warning sign of dangerously deteriorating air in a coal mine,' added Hedges, who is also one of the world's foremost authorities on amphibians and reptiles. ‘When frogs start disappearing, other species will follow and the Haitian people will suffer, as well, from this environmental catastrophe.'
One species already breeding in captivity
Hedges recently relocated ten critically endangered species of frogs from Haiti to a captive-breeding programme at Philadelphia Zoo. One of these species already has begun breeding, laying eggs, and producing hatchlings. Hedges has discovered at least five new frog species during three expeditions to Haiti this year, but he was not able to find two species that may now be extinct because they have not been seen there for 25 years. His scientific descriptions of the new species will be published in future issues of research journals.
The rescue mission led by Hedges is part of a new effort supported by the National Science Foundation to determine which species of amphibians and reptiles currently survive in Haiti, to pinpoint their locations, to discover any new species that previously were not documented scientifically, to relocate live populations of frogs for captive breeding, and to deep-freeze cells at Penn State.
Deep freezing some frogs in case they die out in Haiti
‘Captive breeding and cryobanking are two efforts to preserve the species in case they become extinct in Haiti,' said Hedges, who is one of the few scientists worldwide who have established cryobanking programmes in their labs for endangered frogs and other species.
Cryobanking involves the preservation of cells and DNA in liquid nitrogen that will permit whole-animal cloning, if necessary, in the future. ‘These are time-consuming and costly backup plans to save species, normally reserved for those species closest to extinction,' Hedges said. ‘The goal is to release offspring of rescued frogs in Haiti if and when their forest habitat improves.'
Hedges and the Philadelphia Zoo also are working with the Haitian government and non-governmental agencies to train Haitians in this conservation research so that they can develop the capacity to breed these species in Haiti.
Third of world's frogs face extinction - but 92 per cent of Haiti's frogs are threatened
Frog species have been disappearing worldwide during the past ten to 20 years, and one-third of the Earth's 6,000 frog species are now threatened with extinction. But in Haiti, 92 per cent of Haiti's 50 frog species are threatened - the highest percentage of any country in the world.
‘We found that as many as 26 species occur together in the isolated mountain forests of southwest Haiti,' said Hedges, ‘greatly increasing the threat of mass extinctions when the forests there are cut down.' Of the 50 frog species in Haiti, two-thirds - 30 species - live only in Haiti and do not occur in the neighboring Dominican Republic.
Haiti's lush forests have become a lunar landscape
‘Less than one per cent of the original forest is left in Haiti, which is a lower percentage than in any other country that I know of,' Hedges added. ‘There definitely is no other place in the western half of the world - and some scientists would argue in the entire world - where the extinction threat is greater than in Haiti."
Hedges explained that the forests of Haiti are disappearing because the trees were being cut down to produce charcoal for the 10-million Haitian people who have few other sources of cooking fuel.
‘Forests from some entire mountains now have been removed completely. In places,' said Hedges. ‘It looks like a lunar landscape, with nearly all the soil washed away and only the rocks and some weeds left behind."
‘The pressure for cutting down the forests is coming from a whole island nation of people needing cooking fuel - a problem requiring economic and possibly engineering solutions and needing the help of major international conservation organisations and government agencies,' said Philippe Bayard, President of the Audubon Society of Haiti and collaborator with Hedges in efforts to save Haiti's biodiversity. ‘Unless effective help arrives soon, it is inevitable that there will be mass extinctions, and I think they are in progress.'
http://www.wildlifeextra.com/go/news/haiti-extinction.html
Saturday, September 4, 2010
Mass extinction threat - Earth on verge of huge reset button
http://news.yahoo.com/s/livescience/20100902/sc_livescience/massextinctionthreatearthonvergeofhugeresetbutton
Mass extinction threat - Earth on verge of huge reset button
Mass extinctions have served as huge reset buttons that dramatically changed the diversity of species found in oceans all over the world, according to a comprehensive study of fossil records. The findings suggest humans will live in a very different future if they drive animals to extinction, because the loss of each species can alter entire
ecosystems.
Some scientists have speculated that effects of humans - from hunting to climate change - are fueling another great mass extinction. A few go so far as to say we are entering a new geologic epoch, leaving the 10,000-year-old Holocene Epoch behind and entering the Anthropocene Epoch, marked by major changes to global temperatures and ocean chemistry, increased sediment erosion, and changes in biology that range from altered flowering times to shifts in migration patterns of birds and mammals and potential die-offs of tiny organisms that support the entire marine food chain.
Scientists had once thought species diversity could help buffer a group of animals from such die-offs, either keeping them from heading toward extinction or helping them to bounce back. But having many diverse species also proved no guarantee of future success for any one group of animals, given that mass extinctions more or less wiped the slate clean, according to studies such as the latest one.
Then and now
Looking back in time, the diversity of large taxonomic groups (which include lots of species), such as snails or corals, mostly hovered around a certain equilibrium point that represented a diversity limit of species' numbers. But that diversity limit also appears to have changed spontaneously throughout Earth's history about every 200 million years.
How today's extinction crisis - species today go extinct at a rate that may range from 10 to 100 times the so-called background extinction rate - may change the face of the planet and its species goes beyond what
humans can predict, the researchers say.
"The main implication is that we're really rolling the dice," said John Alroy, a paleobiologist at Macquarie University in Sydney, Australia. "We don't know which groups will suffer the most, which groups will rebound the most quickly, or which ones will end up with higher or lower long-term equilibrium diversity levels."
What seems certain is that the fate of each animal group will differ greatly, Alroy said.
His analysis, detailed in the Sept. 3 issue of the journal Science, is based on almost 100,000 fossil collections in the Paleobiology Database (PaleoDB).
The findings revealed various examples of diversity shifts, including one that took place in a group of ocean bottom-dwelling bivalves called brachiopods, which are similar to clams and oysters. They dominated the
Paleozoic era from 540 million to 250 million years ago, and branched out into new species during two huge adaptive spurts of growth in diversity - each time followed by a big crash.
The brachiopods then reached a low, but steady, equilibrium over the past 250 million years in which there wasn't a surge or a crash in species' numbers, and still live on today as a rare group of marine animals.
Counting creatures better
In the past, researchers have typically counted species in the fossil record by randomly drawing a set number of samples from each time period - a method that can leave out less common species. In fact two studies using the PaleoDB used this approach. Instead, Alroy used a new approach called shareholder sampling, in which
he tracked how frequently certain groups appeared in the fossil record, and then counted enough samples until he hit a target number representative of the proportion for each group.
"In some sense the older methods are a little like the American voting system - the first-past-the-post-winner method basically makes minority views invisible," said Charles Marshall, a paleontologist at the University of California, Berkeley, who did not take part in the study. "However, with proportional systems, minority views still get seats in parliament."
Marshall added that the study was the "most thorough quantitative analysis to date using global marine data." But he added that researchers will probably debate whether the PaleoDB data represents a complete-enough picture of the fossil record. Nothing lasts forever
The idea that rules of diversity change should not come as a surprise for most researchers, according to Marshall.
"To me, the really interesting possibility is that some groups might not yet be close enough to their caps to have those caps be manifest yet," Marshall told LiveScience. Or "evolutionary innovation" might happen so quickly that new groups emerged to increase overall diversity, even if each sub-group reached a cap on diversity.
If anything, the record of past extinctions has shown the difficulty of predicting which groups win out in the long run. "Surviving is one thing and recovering is another," said Marshall, who wrote a Perspectives piece about the study in the same issue of Science.
One of the few consistent patterns is that growth spurts in diversity can apparently happen at any time, according to Alroy. He added that the background extinction of individual species has also remained consistent - the average species lasts just a few million years Of course, the ongoing extinction crisis of modern times goes far beyond the background extinction rate. Alroy noted that it could not only wipe out entire branches of evolutionary history, but may also change the ecosystems shaped by each species.
That means today's species matter for environments around the world, and so humans can't simply expect replacements from the diverse species of the future.
"If we lose all the reef builders, we may not get back the physical reefs for millions of years no matter how fast we get back all the species diversity in a simple sense," Alroy said.
Mass extinction threat - Earth on verge of huge reset button
Mass extinctions have served as huge reset buttons that dramatically changed the diversity of species found in oceans all over the world, according to a comprehensive study of fossil records. The findings suggest humans will live in a very different future if they drive animals to extinction, because the loss of each species can alter entire
ecosystems.
Some scientists have speculated that effects of humans - from hunting to climate change - are fueling another great mass extinction. A few go so far as to say we are entering a new geologic epoch, leaving the 10,000-year-old Holocene Epoch behind and entering the Anthropocene Epoch, marked by major changes to global temperatures and ocean chemistry, increased sediment erosion, and changes in biology that range from altered flowering times to shifts in migration patterns of birds and mammals and potential die-offs of tiny organisms that support the entire marine food chain.
Scientists had once thought species diversity could help buffer a group of animals from such die-offs, either keeping them from heading toward extinction or helping them to bounce back. But having many diverse species also proved no guarantee of future success for any one group of animals, given that mass extinctions more or less wiped the slate clean, according to studies such as the latest one.
Then and now
Looking back in time, the diversity of large taxonomic groups (which include lots of species), such as snails or corals, mostly hovered around a certain equilibrium point that represented a diversity limit of species' numbers. But that diversity limit also appears to have changed spontaneously throughout Earth's history about every 200 million years.
How today's extinction crisis - species today go extinct at a rate that may range from 10 to 100 times the so-called background extinction rate - may change the face of the planet and its species goes beyond what
humans can predict, the researchers say.
"The main implication is that we're really rolling the dice," said John Alroy, a paleobiologist at Macquarie University in Sydney, Australia. "We don't know which groups will suffer the most, which groups will rebound the most quickly, or which ones will end up with higher or lower long-term equilibrium diversity levels."
What seems certain is that the fate of each animal group will differ greatly, Alroy said.
His analysis, detailed in the Sept. 3 issue of the journal Science, is based on almost 100,000 fossil collections in the Paleobiology Database (PaleoDB).
The findings revealed various examples of diversity shifts, including one that took place in a group of ocean bottom-dwelling bivalves called brachiopods, which are similar to clams and oysters. They dominated the
Paleozoic era from 540 million to 250 million years ago, and branched out into new species during two huge adaptive spurts of growth in diversity - each time followed by a big crash.
The brachiopods then reached a low, but steady, equilibrium over the past 250 million years in which there wasn't a surge or a crash in species' numbers, and still live on today as a rare group of marine animals.
Counting creatures better
In the past, researchers have typically counted species in the fossil record by randomly drawing a set number of samples from each time period - a method that can leave out less common species. In fact two studies using the PaleoDB used this approach. Instead, Alroy used a new approach called shareholder sampling, in which
he tracked how frequently certain groups appeared in the fossil record, and then counted enough samples until he hit a target number representative of the proportion for each group.
"In some sense the older methods are a little like the American voting system - the first-past-the-post-winner method basically makes minority views invisible," said Charles Marshall, a paleontologist at the University of California, Berkeley, who did not take part in the study. "However, with proportional systems, minority views still get seats in parliament."
Marshall added that the study was the "most thorough quantitative analysis to date using global marine data." But he added that researchers will probably debate whether the PaleoDB data represents a complete-enough picture of the fossil record. Nothing lasts forever
The idea that rules of diversity change should not come as a surprise for most researchers, according to Marshall.
"To me, the really interesting possibility is that some groups might not yet be close enough to their caps to have those caps be manifest yet," Marshall told LiveScience. Or "evolutionary innovation" might happen so quickly that new groups emerged to increase overall diversity, even if each sub-group reached a cap on diversity.
If anything, the record of past extinctions has shown the difficulty of predicting which groups win out in the long run. "Surviving is one thing and recovering is another," said Marshall, who wrote a Perspectives piece about the study in the same issue of Science.
One of the few consistent patterns is that growth spurts in diversity can apparently happen at any time, according to Alroy. He added that the background extinction of individual species has also remained consistent - the average species lasts just a few million years Of course, the ongoing extinction crisis of modern times goes far beyond the background extinction rate. Alroy noted that it could not only wipe out entire branches of evolutionary history, but may also change the ecosystems shaped by each species.
That means today's species matter for environments around the world, and so humans can't simply expect replacements from the diverse species of the future.
"If we lose all the reef builders, we may not get back the physical reefs for millions of years no matter how fast we get back all the species diversity in a simple sense," Alroy said.
Mass extinction threat - Earth on verge of huge reset button
http://news.yahoo.com/s/livescience/20100902/sc_livescience/massextinctionthreatearthonvergeofhugeresetbutton
Mass extinction threat - Earth on verge of huge reset button
Mass extinctions have served as huge reset buttons that dramatically changed the diversity of species found in oceans all over the world, according to a comprehensive study of fossil records. The findings suggest humans will live in a very different future if they drive animals to extinction, because the loss of each species can alter entire
ecosystems.
Some scientists have speculated that effects of humans - from hunting to climate change - are fueling another great mass extinction. A few go so far as to say we are entering a new geologic epoch, leaving the 10,000-year-old Holocene Epoch behind and entering the Anthropocene Epoch, marked by major changes to global temperatures and ocean chemistry, increased sediment erosion, and changes in biology that range from altered flowering times to shifts in migration patterns of birds and mammals and potential die-offs of tiny organisms that support the entire marine food chain.
Scientists had once thought species diversity could help buffer a group of animals from such die-offs, either keeping them from heading toward extinction or helping them to bounce back. But having many diverse species also proved no guarantee of future success for any one group of animals, given that mass extinctions more or less wiped the slate clean, according to studies such as the latest one.
Then and now
Looking back in time, the diversity of large taxonomic groups (which include lots of species), such as snails or corals, mostly hovered around a certain equilibrium point that represented a diversity limit of species' numbers. But that diversity limit also appears to have changed spontaneously throughout Earth's history about every 200 million years.
How today's extinction crisis - species today go extinct at a rate that may range from 10 to 100 times the so-called background extinction rate - may change the face of the planet and its species goes beyond what
humans can predict, the researchers say.
"The main implication is that we're really rolling the dice," said John Alroy, a paleobiologist at Macquarie University in Sydney, Australia. "We don't know which groups will suffer the most, which groups will rebound the most quickly, or which ones will end up with higher or lower long-term equilibrium diversity levels."
What seems certain is that the fate of each animal group will differ greatly, Alroy said.
His analysis, detailed in the Sept. 3 issue of the journal Science, is based on almost 100,000 fossil collections in the Paleobiology Database (PaleoDB).
The findings revealed various examples of diversity shifts, including one that took place in a group of ocean bottom-dwelling bivalves called brachiopods, which are similar to clams and oysters. They dominated the
Paleozoic era from 540 million to 250 million years ago, and branched out into new species during two huge adaptive spurts of growth in diversity - each time followed by a big crash.
The brachiopods then reached a low, but steady, equilibrium over the past 250 million years in which there wasn't a surge or a crash in species' numbers, and still live on today as a rare group of marine animals.
Counting creatures better
In the past, researchers have typically counted species in the fossil record by randomly drawing a set number of samples from each time period - a method that can leave out less common species. In fact two studies using the PaleoDB used this approach. Instead, Alroy used a new approach called shareholder sampling, in which
he tracked how frequently certain groups appeared in the fossil record, and then counted enough samples until he hit a target number representative of the proportion for each group.
"In some sense the older methods are a little like the American voting system - the first-past-the-post-winner method basically makes minority views invisible," said Charles Marshall, a paleontologist at the University of California, Berkeley, who did not take part in the study. "However, with proportional systems, minority views still get seats in parliament."
Marshall added that the study was the "most thorough quantitative analysis to date using global marine data." But he added that researchers will probably debate whether the PaleoDB data represents a complete-enough picture of the fossil record. Nothing lasts forever
The idea that rules of diversity change should not come as a surprise for most researchers, according to Marshall.
"To me, the really interesting possibility is that some groups might not yet be close enough to their caps to have those caps be manifest yet," Marshall told LiveScience. Or "evolutionary innovation" might happen so quickly that new groups emerged to increase overall diversity, even if each sub-group reached a cap on diversity.
If anything, the record of past extinctions has shown the difficulty of predicting which groups win out in the long run. "Surviving is one thing and recovering is another," said Marshall, who wrote a Perspectives piece about the study in the same issue of Science.
One of the few consistent patterns is that growth spurts in diversity can apparently happen at any time, according to Alroy. He added that the background extinction of individual species has also remained consistent - the average species lasts just a few million years Of course, the ongoing extinction crisis of modern times goes far beyond the background extinction rate. Alroy noted that it could not only wipe out entire branches of evolutionary history, but may also change the ecosystems shaped by each species.
That means today's species matter for environments around the world, and so humans can't simply expect replacements from the diverse species of the future.
"If we lose all the reef builders, we may not get back the physical reefs for millions of years no matter how fast we get back all the species diversity in a simple sense," Alroy said.
Mass extinction threat - Earth on verge of huge reset button
Mass extinctions have served as huge reset buttons that dramatically changed the diversity of species found in oceans all over the world, according to a comprehensive study of fossil records. The findings suggest humans will live in a very different future if they drive animals to extinction, because the loss of each species can alter entire
ecosystems.
Some scientists have speculated that effects of humans - from hunting to climate change - are fueling another great mass extinction. A few go so far as to say we are entering a new geologic epoch, leaving the 10,000-year-old Holocene Epoch behind and entering the Anthropocene Epoch, marked by major changes to global temperatures and ocean chemistry, increased sediment erosion, and changes in biology that range from altered flowering times to shifts in migration patterns of birds and mammals and potential die-offs of tiny organisms that support the entire marine food chain.
Scientists had once thought species diversity could help buffer a group of animals from such die-offs, either keeping them from heading toward extinction or helping them to bounce back. But having many diverse species also proved no guarantee of future success for any one group of animals, given that mass extinctions more or less wiped the slate clean, according to studies such as the latest one.
Then and now
Looking back in time, the diversity of large taxonomic groups (which include lots of species), such as snails or corals, mostly hovered around a certain equilibrium point that represented a diversity limit of species' numbers. But that diversity limit also appears to have changed spontaneously throughout Earth's history about every 200 million years.
How today's extinction crisis - species today go extinct at a rate that may range from 10 to 100 times the so-called background extinction rate - may change the face of the planet and its species goes beyond what
humans can predict, the researchers say.
"The main implication is that we're really rolling the dice," said John Alroy, a paleobiologist at Macquarie University in Sydney, Australia. "We don't know which groups will suffer the most, which groups will rebound the most quickly, or which ones will end up with higher or lower long-term equilibrium diversity levels."
What seems certain is that the fate of each animal group will differ greatly, Alroy said.
His analysis, detailed in the Sept. 3 issue of the journal Science, is based on almost 100,000 fossil collections in the Paleobiology Database (PaleoDB).
The findings revealed various examples of diversity shifts, including one that took place in a group of ocean bottom-dwelling bivalves called brachiopods, which are similar to clams and oysters. They dominated the
Paleozoic era from 540 million to 250 million years ago, and branched out into new species during two huge adaptive spurts of growth in diversity - each time followed by a big crash.
The brachiopods then reached a low, but steady, equilibrium over the past 250 million years in which there wasn't a surge or a crash in species' numbers, and still live on today as a rare group of marine animals.
Counting creatures better
In the past, researchers have typically counted species in the fossil record by randomly drawing a set number of samples from each time period - a method that can leave out less common species. In fact two studies using the PaleoDB used this approach. Instead, Alroy used a new approach called shareholder sampling, in which
he tracked how frequently certain groups appeared in the fossil record, and then counted enough samples until he hit a target number representative of the proportion for each group.
"In some sense the older methods are a little like the American voting system - the first-past-the-post-winner method basically makes minority views invisible," said Charles Marshall, a paleontologist at the University of California, Berkeley, who did not take part in the study. "However, with proportional systems, minority views still get seats in parliament."
Marshall added that the study was the "most thorough quantitative analysis to date using global marine data." But he added that researchers will probably debate whether the PaleoDB data represents a complete-enough picture of the fossil record. Nothing lasts forever
The idea that rules of diversity change should not come as a surprise for most researchers, according to Marshall.
"To me, the really interesting possibility is that some groups might not yet be close enough to their caps to have those caps be manifest yet," Marshall told LiveScience. Or "evolutionary innovation" might happen so quickly that new groups emerged to increase overall diversity, even if each sub-group reached a cap on diversity.
If anything, the record of past extinctions has shown the difficulty of predicting which groups win out in the long run. "Surviving is one thing and recovering is another," said Marshall, who wrote a Perspectives piece about the study in the same issue of Science.
One of the few consistent patterns is that growth spurts in diversity can apparently happen at any time, according to Alroy. He added that the background extinction of individual species has also remained consistent - the average species lasts just a few million years Of course, the ongoing extinction crisis of modern times goes far beyond the background extinction rate. Alroy noted that it could not only wipe out entire branches of evolutionary history, but may also change the ecosystems shaped by each species.
That means today's species matter for environments around the world, and so humans can't simply expect replacements from the diverse species of the future.
"If we lose all the reef builders, we may not get back the physical reefs for millions of years no matter how fast we get back all the species diversity in a simple sense," Alroy said.
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