Mostrando entradas con la etiqueta The Evolution. Mostrar todas las entradas
Mostrando entradas con la etiqueta The Evolution. Mostrar todas las entradas

sábado, 1 de diciembre de 2012

nsf.gov - Discovery - Studying Evolution in Action

Researchers apply biological and digital approaches to better understand underlying factors:

http://www.nsf.gov/news/mmg/media/images/terrestrial-robots-lowres3.jpeg
One type of research done at BEACON includes the design of robots that cooperate to achieve a common goal and get rewarded or punished based on their interaction.
Credit: Philip McKinley, Michigan State University
Download the high-resolution JPEG version of the image. (165 KB)
http://www.nsf.gov/news/mmg/media/images/BEACON_Hyenas_and_Lion3.jpeg
Biologists study mammalian behavior, including hyenas using computational theory. One example is studying how cooperative behavior evolves among competing predators. In this picture, hyenas and lion feed on carcass in Masai Mara National Reserve, Kenya.
Credit: Laura Smale, Michigan State University
Download the high-resolution JPEG version of the image. (77 KB)
http://www.nsf.gov/news/mmg/media/images/webots-environment-final3.jpeg
3D image of intelligent vehicle systems experiments conducted in the webots simulation environment. The scenario in particular shows two simulated vehicle controllers capable of adaptive cruise control and lane keeping. Evolutionary computation was used to introduce uncertainty at the sensory level and thereby explore how controllers were affected.
Credit: Michigan State University
Download the high-resolution JPEG version of the image. (88 KB)


Evolution is not just something from the past. It also happens in real time. Bacteria mutate and resist antibiotics. Viruses reinvent themselves and elude new medications. Animals adapt their behavior in response to a changing planet.
Traditionally, researchers have studied evolution by looking back, often using fossils and other relics to understand how organisms have changed over time in order to survive. It is an established and valuable approach.
But it is not the only one. Thanks to new sophisticated computational technology, scientists now can combine field observations with digital evolution systems, enabling them to answer important biological questions, as well as solve non-biological problems using evolutionary methods.
"It's not that what we're doing won't shed light on evolution over millions of years, but we also are able to study things we can actually observe with our eyes," says Erik Goodman, director of the BEACON Center for the Study of Evolution in Action, which is conducting much of this work. "We are looking at evolution in the real world."
Computer software allows the researchers to create digital organisms, similar in some ways to real bacteria and viruses, for example, that can copy themselves, make mistakes and cause mutations, essentially behaving like their real life counterparts. The difference, however, is that the digital creatures can do it in a fraction of the time.
"For example, if we find some phenomenon going on in the lab that we can't explain, we can take it into the digital world and get an explanation of how it might work," Goodman says. "Then we can take it back to the lab to see if that explanation holds in the real world."
Engineers also can use engineering simulation software to create an environment where new product designs can "evolve." With each generation, the computer makes random mutations in existing designs in order to produce new ones; the simulation software then evaluates each new line and allows the better ones to survive, much like evolution in nature. Computers also can "evolve" new robot programs, making use of natural selection and enabling the machines to respond to human or animal interaction.
"How, for example, would you design robots that could cooperate with each other to work together toward a unified goal, to reward them when they cooperate and punish them when they cheat?" says evolutionary biologist Richard Lenski, professor of microbiology and molecular genetics at Michigan State. "Evolution solves some of these difficult problems, and this is a way of allowing computer programs themselves to engage in their own form of evolution and natural selection."
Evolution is not just something from the past. It also happens in real time. Bacteria mutate and resist antibiotics. Viruses reinvent themselves and elude new medications. Animals adapt their behavior in response to a changing planet.
Traditionally, researchers have studied evolution by looking back, often using fossils and other relics to understand how organisms have changed over time in order to survive. It is an established and valuable approach.
But it is not the only one. Thanks to new sophisticated computational technology, scientists now can combine field observations with digital evolution systems, enabling them to answer important biological questions, as well as solve non-biological problems using evolutionary methods.
"It's not that what we're doing won't shed light on evolution over millions of years, but we also are able to study things we can actually observe with our eyes," says Erik Goodman, director of the BEACON Center for the Study of Evolution in Action, which is conducting much of this work. "We are looking at evolution in the real world."
Computer software allows the researchers to create digital organisms, similar in some ways to real bacteria and viruses, for example, that can copy themselves, make mistakes and cause mutations, essentially behaving like their real life counterparts. The difference, however, is that the digital creatures can do it in a fraction of the time.
"For example, if we find some phenomenon going on in the lab that we can't explain, we can take it into the digital world and get an explanation of how it might work," Goodman says. "Then we can take it back to the lab to see if that explanation holds in the real world."
Engineers also can use engineering simulation software to create an environment where new product designs can "evolve." With each generation, the computer makes random mutations in existing designs in order to produce new ones; the simulation software then evaluates each new line and allows the better ones to survive, much like evolution in nature. Computers also can "evolve" new robot programs, making use of natural selection and enabling the machines to respond to human or animal interaction.
"How, for example, would you design robots that could cooperate with each other to work together toward a unified goal, to reward them when they cooperate and punish them when they cheat?" says evolutionary biologist Richard Lenski, professor of microbiology and molecular genetics at Michigan State. "Evolution solves some of these difficult problems, and this is a way of allowing computer programs themselves to engage in their own form of evolution and natural selection."
The National Science Foundation is supporting the center with $25 million over five years, with the potential for a one-time renewal after the first cycle. The center, launched last year, is located at Michigan State University with partners at North Carolina A&T State University, the University of Idaho, the University of Texas at Austin and the University of Washington.
BEACON researchers include biologists, engineers, and computer scientists who collaborate on biological and digital evolution, and evolutionary approaches to engineering. The center also has an artist-in-residence who examines evolution through an artistic lens.
Ultimately, their work not only will provide a better understanding of evolution, but also potentially could prompt medical innovations, such as new vaccines to target elusive viruses, and improved product designs.
"We aren't doing medical research, but trying to understand underlying mechanisms," Goodman says. "If we knew more about how certain viruses evolve, for example, we could target the weak points to develop better vaccines. In the area of product design, for example, we have designed new parts for automobiles using computer programs based on evolution. The computer programs can generate a bunch of designs at random, and the better ones become the 'parents' of the next generation. It works like natural selection, it mimics the evolutionary process."
Kay E. Holekamp, professor of zoology at Michigan State, studies mammalian behavior, focusing on hyenas, and is collaborating with BEACON engineers to develop robotic hyenas that someday will interact with real ones. The goal is to help answer long-standing questions about how the animals communicate with one another. The scientists still are in the planning stages, but Holekamp hopes to be using these robots in her research within several years.
"Hyenas ‘talk' to each other using different modalities," she says. "They engage in posturing, they position their tails and their ears in a certain way. They vocalize. They emit multiple signals. I can't ask the hyenas to stop, while I work with one of them, but I could program the robots. If I can manipulate the robots from my car, and monitor the hyenas' responses, I can understand what they are communicating. I couldn't possibly do that in the real environment."
Together with her BEACON collaborators, she also is developing a computational theory of how cooperative behavior evolves among competing predators, again, focusing on hyenas. She plans to simulate cooperative hyena behavior, specifically how they collaborate to steal food from lions, and how they compete among themselves for the food when they get it.
"Our research team will first videotape the events in nature, and then model them with computational simulations in order to study their evolutionary origins, including the conditions under which each behavior is effective," she says. "The result will be a computational theory of how and why competing predators cooperate, as well as computational methods for evolving complex cooperation among intelligent agents in virtual environments."
She adds: "Hyenas are disastrously difficult to study in terms of evolution because they reproduce so slowly. They also appear to violate a lot of the rules of mammalian biology. For example, the roles of male and females are completely reversed. In most mammals, the males are bigger and stronger and more aggressive. In hyenas, it's the females.
"Also, these animals live at the top of the food chain, but their societies are nothing like those of other carnivores," she continues. "They violate the rules of density. Most The National Science Foundationat the top are relatively rare, but hyenas are plentiful, living in big groups that can contain as many as 90 individuals. I think these particular animals are among the most interesting on Earth."
In another way of looking at evolution, BEACON artist-in-residence Adam Brown is creating a robotic art project made up of about 150 three-dimensional sculptural robots mounted on walls and capable of communicating with each other, and will use computational evolution programs to discover the kinds of behaviors that will inspire interaction with humans.
Brown explains: "Let's say you want to evolve robots who want to be touched by humans--what kinds of behaviors must the robots engage in to encourage this? Flashing lights? Sounds? We use the tools of evolution--evolutionary algorithms--to solve the problem. Over a five-minute span you can have more than 10,000 generations for a specific task, something you can do with computational technology that you can't do in the real world."
In another piece connecting evolution to art, Brown and Robert Root-Bernstein, professor of physiology at Michigan State, built an art installation recreating the classic 1952 Miller-Urey experiment on the origins of life, simulating what is thought to be Earth's original atmosphere by combining hydrogen, ammonia and methane in a glass chamber, with zapping electricity as "lightning" to form amino acids, which are critical to life.
The piece, called "Origins of Life Experiment #1.2," reinterprets the work of physicist Harold Urey, who proposed that it might be possible to recreate the atmosphere of the primordial Earth in a closed container and synthesize organic molecules by adding an energy source such as lightning to the mix. Stanley Miller, a graduate student, conducted the experiment producing, within days, several amino acids. The Miller-Urey experiment quickly became a scientific and public icon of origins of life experimentation.
"This experiment was inspirational to me," says Brown, associate professor of electronic art and intermedia in Michigan State's department of art and art history. "I wanted to take this science experiment and put it into the context of art."
In addition to the research and art, BEACON center scientists have established summer programs for high school students and undergraduates, and are working with graduate students to expose them to new cross-disciplinary concepts of evolutionary and computational biology.
"By having both of these systems available, the students learn a different way of formulating their hypotheses, and asking their questions," Goodman says. "Then, when they start working with digital organisms, they also can get results the next day and the next week - rather than having to work for years in the lab."
--  Marlene Cimons, National Science Foundation
Investigators Xiaobo Tan
Erik Goodman
Kay Holekamp
Kim Scribner
Charles Ofria
Jeffrey French
Richard Lenski
Robert Pennock
Philip McKinley
Janette Boughman
Stephen Glickman
Related Institutions/Organizations Michigan State University
 is supporting the center with $25 million over five years, with the potential for a one-time renewal after the first cycle. The center, launched last year, is located at Michigan State University with partners at North Carolina A&T State University, the University of Idaho, the University of Texas at Austin and the University of Washington.
BEACON researchers include biologists, engineers, and computer scientists who collaborate on biological and digital evolution, and evolutionary approaches to engineering. The center also has an artist-in-residence who examines evolution through an artistic lens.
Ultimately, their work not only will provide a better understanding of evolution, but also potentially could prompt medical innovations, such as new vaccines to target elusive viruses, and improved product designs.
"We aren't doing medical research, but trying to understand underlying mechanisms," Goodman says. "If we knew more about how certain viruses evolve, for example, we could target the weak points to develop better vaccines. In the area of product design, for example, we have designed new parts for automobiles using computer programs based on evolution. The computer programs can generate a bunch of designs at random, and the better ones become the 'parents' of the next generation. It works like natural selection, it mimics the evolutionary process."
Kay E. Holekamp, professor of zoology at Michigan State, studies mammalian behavior, focusing on hyenas, and is collaborating with BEACON engineers to develop robotic hyenas that someday will interact with real ones. The goal is to help answer long-standing questions about how the animals communicate with one another. The scientists still are in the planning stages, but Holekamp hopes to be using these robots in her research within several years.
"Hyenas ‘talk' to each other using different modalities," she says. "They engage in posturing, they position their tails and their ears in a certain way. They vocalize. They emit multiple signals. I can't ask the hyenas to stop, while I work with one of them, but I could program the robots. If I can manipulate the robots from my car, and monitor the hyenas' responses, I can understand what they are communicating. I couldn't possibly do that in the real environment."
Together with her BEACON collaborators, she also is developing a computational theory of how cooperative behavior evolves among competing predators, again, focusing on hyenas. She plans to simulate cooperative hyena behavior, specifically how they collaborate to steal food from lions, and how they compete among themselves for the food when they get it.
"Our research team will first videotape the events in nature, and then model them with computational simulations in order to study their evolutionary origins, including the conditions under which each behavior is effective," she says. "The result will be a computational theory of how and why competing predators cooperate, as well as computational methods for evolving complex cooperation among intelligent agents in virtual environments."
She adds: "Hyenas are disastrously difficult to study in terms of evolution because they reproduce so slowly. They also appear to violate a lot of the rules of mammalian biology. For example, the roles of male and females are completely reversed. In most mammals, the males are bigger and stronger and more aggressive. In hyenas, it's the females.
"Also, these animals live at the top of the food chain, but their societies are nothing like those of other carnivores," she continues. "They violate the rules of density. Most mammals at the top are relatively rare, but hyenas are plentiful, living in big groups that can contain as many as 90 individuals. I think these particular animals are among the most interesting on Earth."
In another way of looking at evolution, BEACON artist-in-residence Adam Brown is creating a robotic art project made up of about 150 three-dimensional sculptural robots mounted on walls and capable of communicating with each other, and will use computational evolution programs to discover the kinds of behaviors that will inspire interaction with humans.
Brown explains: "Let's say you want to evolve robots who want to be touched by humans--what kinds of behaviors must the robots engage in to encourage this? Flashing lights? Sounds? We use the tools of evolution--evolutionary algorithms--to solve the problem. Over a five-minute span you can have more than 10,000 generations for a specific task, something you can do with computational technology that you can't do in the real world."
In another piece connecting evolution to art, Brown and Robert Root-Bernstein, professor of physiology at Michigan State, built an art installation recreating the classic 1952 Miller-Urey experiment on the origins of life, simulating what is thought to be Earth's original atmosphere by combining hydrogen, ammonia and methane in a glass chamber, with zapping electricity as "lightning" to form amino acids, which are critical to life.
The piece, called "Origins of Life Experiment #1.2," reinterprets the work of physicist Harold Urey, who proposed that it might be possible to recreate the atmosphere of the primordial Earth in a closed container and synthesize organic molecules by adding an energy source such as lightning to the mix. Stanley Miller, a graduate student, conducted the experiment producing, within days, several amino acids. The Miller-Urey experiment quickly became a scientific and public icon of origins of life experimentation.
"This experiment was inspirational to me," says Brown, associate professor of electronic art and intermedia in Michigan State's department of art and art history. "I wanted to take this science experiment and put it into the context of art."
In addition to the research and art, BEACON center scientists have established summer programs for high school students and undergraduates, and are working with graduate students to expose them to new cross-disciplinary concepts of evolutionary and computational biology.
"By having both of these systems available, the students learn a different way of formulating their hypotheses, and asking their questions," Goodman says. "Then, when they start working with digital organisms, they also can get results the next day and the next week - rather than having to work for years in the lab."
--  Marlene Cimons, National Science Foundation
Investigators Xiaobo Tan
Erik Goodman
Kay Holekamp
Kim Scribner
Charles Ofria
Jeffrey French
Richard Lenski
Robert Pennock
Philip McKinley
Janette Boughman
Stephen Glickman
Related Institutions/Organizations Michigan State University
 Evolution is not just something from the past. It also happens in real time. Bacteria mutate and resist antibiotics. Viruses reinvent themselves and elude new medications. Animals adapt their behavior in response to a changing planet.
Traditionally, researchers have studied evolution by looking back, often using fossils and other relics to understand how organisms have changed over time in order to survive. It is an established and valuable approach.
But it is not the only one. Thanks to new sophisticated computational technology, scientists now can combine field observations with digital evolution systems, enabling them to answer important biological questions, as well as solve non-biological problems using evolutionary methods.
"It's not that what we're doing won't shed light on evolution over millions of years, but we also are able to study things we can actually observe with our eyes," says Erik Goodman, director of the BEACON Center for the Study of Evolution in Action, which is conducting much of this work. "We are looking at evolution in the real world."
Computer software allows the researchers to create digital organisms, similar in some ways to real bacteria and viruses, for example, that can copy themselves, make mistakes and cause mutations, essentially behaving like their real life counterparts. The difference, however, is that the digital creatures can do it in a fraction of the time.
"For example, if we find some phenomenon going on in the lab that we can't explain, we can take it into the digital world and get an explanation of how it might work," Goodman says. "Then we can take it back to the lab to see if that explanation holds in the real world."
Engineers also can use engineering simulation software to create an environment where new product designs can "evolve." With each generation, the computer makes random mutations in existing designs in order to produce new ones; the simulation software then evaluates each new line and allows the better ones to survive, much like evolution in nature. Computers also can "evolve" new robot programs, making use of natural selection and enabling the machines to respond to human or animal interaction.
"How, for example, would you design robots that could cooperate with each other to work together toward a unified goal, to reward them when they cooperate and punish them when they cheat?" says evolutionary biologist Richard Lenski, professor of microbiology and molecular genetics at Michigan State. "Evolution solves some of these difficult problems, and this is a way of allowing computer programs themselves to engage in their own form of evolution and natural selection."
The National Science Foundation is supporting the center with $25 million over five years, with the potential for a one-time renewal after the first cycle. The center, launched last year, is located at Michigan State University with partners at North Carolina A&T State University, the University of Idaho, the University of Texas at Austin and the University of Washington.
BEACON researchers include biologists, engineers, and computer scientists who collaborate on biological and digital evolution, and evolutionary approaches to engineering. The center also has an artist-in-residence who examines evolution through an artistic lens.
Ultimately, their work not only will provide a better understanding of evolution, but also potentially could prompt medical innovations, such as new vaccines to target elusive viruses, and improved product designs.
"We aren't doing medical research, but trying to understand underlying mechanisms," Goodman says. "If we knew more about how certain viruses evolve, for example, we could target the weak points to develop better vaccines. In the area of product design, for example, we have designed new parts for automobiles using computer programs based on evolution. The computer programs can generate a bunch of designs at random, and the better ones become the 'parents' of the next generation. It works like natural selection, it mimics the evolutionary process."
Kay E. Holekamp, professor of zoology at Michigan State, studies mammalian behavior, focusing on hyenas, and is collaborating with BEACON engineers to develop robotic hyenas that someday will interact with real ones. The goal is to help answer long-standing questions about how the animals communicate with one another. The scientists still are in the planning stages, but Holekamp hopes to be using these robots in her research within several years.
"Hyenas ‘talk' to each other using different modalities," she says. "They engage in posturing, they position their tails and their ears in a certain way. They vocalize. They emit multiple signals. I can't ask the hyenas to stop, while I work with one of them, but I could program the robots. If I can manipulate the robots from my car, and monitor the hyenas' responses, I can understand what they are communicating. I couldn't possibly do that in the real environment."
Together with her BEACON collaborators, she also is developing a computational theory of how cooperative behavior evolves among competing predators, again, focusing on hyenas. She plans to simulate cooperative hyena behavior, specifically how they collaborate to steal food from lions, and how they compete among themselves for the food when they get it.
"Our research team will first videotape the events in nature, and then model them with computational simulations in order to study their evolutionary origins, including the conditions under which each behavior is effective," she says. "The result will be a computational theory of how and why competing predators cooperate, as well as computational methods for evolving complex cooperation among intelligent agents in virtual environments."
She adds: "Hyenas are disastrously difficult to study in terms of evolution because they reproduce so slowly. They also appear to violate a lot of the rules of mammalian biology. For example, the roles of male and females are completely reversed. In most mammals, the males are bigger and stronger and more aggressive. In hyenas, it's the females.
"Also, these animals live at the top of the food chain, but their societies are nothing like those of other carnivores," she continues. "They violate the rules of density. Most mammals at the top are relatively rare, but hyenas are plentiful, living in big groups that can contain as many as 90 individuals. I think these particular animals are among the most interesting on Earth."
In another way of looking at evolution, BEACON artist-in-residence Adam Brown is creating a robotic art project made up of about 150 three-dimensional sculptural robots mounted on walls and capable of communicating with each other, and will use computational evolution programs to discover the kinds of behaviors that will inspire interaction with humans.
Brown explains: "Let's say you want to evolve robots who want to be touched by humans--what kinds of behaviors must the robots engage in to encourage this? Flashing lights? Sounds? We use the tools of evolution--evolutionary algorithms--to solve the problem. Over a five-minute span you can have more than 10,000 generations for a specific task, something you can do with computational technology that you can't do in the real world."
In another piece connecting evolution to art, Brown and Robert Root-Bernstein, professor of physiology at Michigan State, built an art installation recreating the classic 1952 Miller-Urey experiment on the origins of life, simulating what is thought to be Earth's original atmosphere by combining hydrogen, ammonia and methane in a glass chamber, with zapping electricity as "lightning" to form amino acids, which are critical to life.
The piece, called "Origins of Life Experiment #1.2," reinterprets the work of physicist Harold Urey, who proposed that it might be possible to recreate the atmosphere of the primordial Earth in a closed container and synthesize organic molecules by adding an energy source such as lightning to the mix. Stanley Miller, a graduate student, conducted the experiment producing, within days, several amino acids. The Miller-Urey experiment quickly became a scientific and public icon of origins of life experimentation.
"This experiment was inspirational to me," says Brown, associate professor of electronic art and intermedia in Michigan State's department of art and art history. "I wanted to take this science experiment and put it into the context of art."
In addition to the research and art, BEACON center scientists have established summer programs for high school students and undergraduates, and are working with graduate students to expose them to new cross-disciplinary concepts of evolutionary and computational biology.
"By having both of these systems available, the students learn a different way of formulating their hypotheses, and asking their questions," Goodman says. "Then, when they start working with digital organisms, they also can get results the next day and the next week - rather than having to work for years in the lab."
--  Marlene Cimons, National Science Foundation
Investigators Xiaobo Tan
Erik Goodman
Kay Holekamp
Kim Scribner
Charles Ofria
Jeffrey French
Richard Lenski
Robert Pennock
Philip McKinley
Janette Boughman
Stephen Glickman

Related Institutions/Organizations Michigan State University

Related Awards #0939454 BEACON: An NSF Center for the Study of Evolution in Action
#0819437 LTREB: Fitness Consequences of Pleiotropic Androgen Effects in Free-Living Mammals
#1059373 II-EN: Evolution Park - An Evolutionary Robotics Habitat for the Study of Crawling, Swimming and Flying Creatures
 
The National Science Foundation
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com

jueves, 23 de febrero de 2012

Science: Evolution of Earliest Horses Driven by Climate Change

Hi My Friends: AL VUELO DE UN QUINDE EL BLOG., When Sifrhippus sandae, the earliest known horse, first appeared in the forests of North America more than 50 million years ago, it would not have been mistaken for a Clydesdale. An artist's reconstruction of a modern horse compared with Sifrhippus.
Credit: Danielle Byerley, UFL

Teeth of Sifrhippus at its larger size with teeth from the same species after its size shrank.
Credit: Kristen Grace, UFL


When Sifrhippus sandae, the earliest known horse, first appeared in the forests of North America more than 50 million years ago, it would not have been mistaken for a Clydesdale.

It weighed in at around 12 pounds--and it was destined to get much smaller over the ensuing millennia.

Sifrhippus lived during the Paleocene-Eocene Thermal Maximum (PETM), a 175,000-year interval of time some 56 million years ago in which average global temperatures rose by about 10 degrees Fahrenheit.

The change was caused by the release of vast amounts of carbon into the atmosphere and oceans.

About a third of mammal species responded with a significant reduction in size during the PETM, some by as much as one-half.

Sifrhippus shrank by about 30 percent, to the size of a small house cat--about 8.5 pounds--in the PETM's first 130,000 years, then rebounded to about 15 pounds in the final 45,000 years of the PETM.

Scientists have assumed that rising temperatures or high concentrations of carbon dioxide primarily caused the "dwarfing" phenomenon in mammals during this period.

New research led by Ross Secord of the University of Nebraska-Lincoln and Jonathan Bloch of the Florida Museum of Natural History at the University of Florida offers evidence of the cause-and-effect relationship between temperature and body size.

Their findings also provide clues to what might happen to animals in the near future from global warming.

In a paper published in this week's issue of the journal Science, Secord, Bloch and colleagues used measurements and geochemical composition of fossil mammal teeth to document a progressive decrease in Sifrhippus' body size that correlates very closely to temperature change over a 130,000-year span.

"The reduction in available oxygen some 50 million years ago led to a reduction in the body size of animal life," says H. Richard Lane, program director in the National Science Foundation's (NSF) Division of Earth Sciences, which funded the research. "What does that say about the future for Earth's animals?"

Bloch said that multiple trails led to the discovery.

One was the fossils themselves, recovered from the Cabin Fork area of the southern Bighorn Basin near Worland, Wyo.

Stephen Chester at Yale, a paper co-author, had the task of measuring the horses' teeth.

What he found when he plotted them through time caught Bloch and Secord by surprise.

"He pointed out that the first horses in the section were much larger than those later on," Bloch says. "I thought something had to be wrong, but he was right and the pattern became more robust as we collected more fossils."

Secord performed the geochemical analysis of the teeth. What he found was an even bigger surprise.

"It was absolutely startling when Ross pulled up the data," Bloch said. "We realized that it was exactly the same pattern that we were seeing with the horse body.

"For the first time, going back into deep time--tens of millions of years--we were able to show that indeed temperature was causing essentially a one-to-one shift in body size in this lineage of horse.

"Because it's over a long enough time, you can argue very strongly that what you're looking at is natural selection and evolution that it's actually corresponding to the shift in temperature and driving the evolution of these horses."

Secord says that the finding raises important questions about how plants and animals will respond to rapid change in the not-too-distant future.

"This has implications for what we might expect to see over the next century or two with climate models that are predicting warming of as much as 4 degrees Centigrade over the next 100 years," he says, which is 7 degrees Fahrenheit.

Those predictions are based largely on the 40 percent increase of atmospheric carbon dioxide levels, from 280 to 392 parts per million, since the start of the Industrial Revolution in the mid-19th century.

Ornithologists, Secord says, have already started to notice that there may be a decrease in body size among birds.

"One of the issues is that warming during the PETM happened much more slowly, over 10,000 to 20,000 years to increase by 10 degrees, whereas now we're expecting it to happen over a century or two."

"So there's a big difference in scale. One of the questions is, 'Are we going to see the same kind of response?' Are animals going to be able to keep up and readjust their body sizes over the next couple of centuries?"

Increased temperatures are not the only change to which animals may have to adapt.

Experiments show that increased atmospheric carbon dioxide lowers the nutritional content of plants, which could have been a secondary driver of dwarfism during the PETM.

Other co-authors of the paper are Doug Boyer of Brooklyn College, Aaron Wood of the Florida Museum of Natural History, Scott Wing of the Smithsonian National Museum of Natural History, Mary Kraus of the University of Colorado-Boulder, Francesca McInerny of Northwestern University and John Krigbaum of the University of Florida.

The research was also funded by University of Nebraska-Lincoln.
-NSF-
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com

Science: A Biodiversity Discovery That Was Waiting in the Wings--Wasp Wings, That Is

Hi My Friends: AL VUELO DE UN QUINDE EL BLOG., Study of wing sizes of two wasp species helps explain huge diversity of shapes and sizes of organisms in nature Two species of tiny Nasonia wasps used to analyze different species wing sizes.
Credit and Larger Version


From spaghetti-like sea anemones to blobby jellyfish to filigreed oak trees, each species in nature is characterized by a unique size and shape. But the evolutionary changes that produce the seemingly limitless diversity of shapes and sizes of organisms on Earth largely remains a mystery. Nevertheless, a better understanding of how cells grow and enable organisms to assume their characteristic sizes and shapes could shed light on diseases that involve cell growth, including cancer and diabetes.

Providing new information about the evolution of the diversity of sizes and shapes in nature is a study identifying genetic differences between two closely related species of Nasonia wasps. These differences give males of one of the Nasonia species small flightless wings and the males of the other Nasonia species flight-worthy wings that are twice as large.

Jack Werren and David Loehlin at the University of Rochester led the research. (Loehlin is now a post-doc at the University of Wisconsin-Madison). Funded by the National Science Foundation (NSF), this week's issue of Science covers the research.

The research team identified the chromosomal location of the gene responsible for wing size in each of the two Nasonia species, the differences between the DNA sequences of these genes, as well as regulatory controls that determine when, where and how long each species' growth gene is turned on.

These genetic differences alter both the locations of growth centers in the wings and the timing of growth during Nasonia development--factors that give each species its distinct wing size. As evidence that the identified genes control wing size, the researchers nearly doubled the wing size of the small-winged species by cross-breeding into it the gene from the big-winged species.

Interestingly, Loehlin says the team's results indicate multiple genetic changes caused the differences in Nasonia wing size-changes, and these changes may have occurred incrementally. "It is possible that the diversity of size and shape differences between other animal species have similar origins in regulator DNA. And the gene we identified is thought to control growth in many other animals, including people."

The researchers suspect that the small winged Nasonia species evolved from the big-winged species, but it is also possible that the two species evolved in the opposite order.

"Understanding the types of changes in DNA that are responsible for evolution is critical to unraveling the causes of life's diversity," says Samuel Scheiner, a program director at NSF. "The recent explosion of new tools for DNA sequencing is now allowing this understanding. This study demonstrates that changes in gene regulation can be important for such evolution."

The two studied species of Nasonia wasps were chosen for this research because their close genetic relationship coupled with the large difference in their wing sizes makes genetic comparisons between them particularly easy. Nasonia wasps have become a model system for studying evolution because their genetics and breeding system simplify the identification of genetic changes behind complex traits.
-NSF-
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com


martes, 17 de enero de 2012

Science: Biologists Replicate Key Evolutionary Step in Life on Earth

Hi My Friends: AL VUELO DE UN QUINDE EL BLOG., More than 500 million years ago, single-celled organisms on Earth's surface began forming multi-cellular clusters that ultimately became plants and animals.

Green cells are undergoing cell death, a cellular division-of-labor--fostering new life.

Credit: Will Ratcliff and Mike Travisano
Multi-cellular 'snowflake' yeast images with a blue cell-wall stain and red dead-cell stain.

Credit: Will Ratcliff and Mike Travisano
First steps in the transition to multi-cellularity: 'snowflake' yeast with dead cells stained red.

Credit: Will Ratcliff and Mike Travisano
A multi-cellular yeast consisting of hundreds of cells.

Credit: Will Ratcliff and Mike Travisano Multi-cellular yeast individuals containing central dead cells, which promote reproduction.

Credit: Will Ratcliff and Mike Travisano Aberrant shapes of multi-cellular yeast's dead cells: break points for reproduction.


Credit: Will Ratcliff and Mike Travisano

More than 500 million years ago, single-celled organisms on Earth's surface began forming multi-cellular clusters that ultimately became plants and animals.
Just how that happened is a question that has eluded evolutionary biologists.
Now scientists have replicated that key step in the laboratory using common Brewer's yeast, a single-celled organism.
The yeast "evolved" into multi-cellular clusters that work together cooperatively, reproduce and adapt to their environment--in essence, they became precursors to life on Earth as it is today.
The results are published in this week's issue of the journal Proceedings of the National Academy of Sciences (PNAS).
"The finding that the division-of-labor evolves so quickly and repeatedly in these 'snowflake' clusters is a big surprise," says George Gilchrist, acting deputy division director of the National Science Foundation's (NSF) Division of Environmental Biology, which funded the research.
"The first step toward multi-cellular complexity seems to be less of an evolutionary hurdle than theory would suggest," says Gilchrist. "This will stimulate a lot of important research questions."
It all started two years ago with a casual comment over coffee that bridging the famous multi-cellularity gap would be "just about the coolest thing we could do," recalled Will Ratcliff and Michael Travisano, scientists at the University of Minnesota (UMN) and authors of the PNAS paper.
Other authors of the paper are Ford Denison and Mark Borrello of UMN.
Then came the big surprise: it wasn't that difficult.
Using yeast cells, culture media and a centrifuge, it only took the biologists one experiment conducted over about 60 days.
"I don't think anyone had ever tried it before," says Ratcliff. "There aren't many scientists doing experimental evolution, and they're trying to answer questions about evolution, not recreate it."
The results have earned praise from evolutionary biologists around the world.
"To understand why the world is full of plants and animals, including humans, we need to know how one-celled organisms made the switch to living as a group, as multi-celled organisms," says Sam Scheiner, program director in NSF's Division of Environmental Biology.
"This study is the first to experimentally observe that transition," says Scheiner, "providing a look at an event that took place hundreds of millions of years ago."
In essence, here's how the experiments worked:
The scientists chose Brewer's yeast, or Saccharomyces cerevisiae, a species of yeast used since ancient times to make bread and beer because it is abundant in nature and grows easily.
They added it to nutrient-rich culture media and allowed the cells to grow for a day in test tubes.
Then they used a centrifuge to stratify the contents by weight.
As the mixture settled, cell clusters landed on the bottom of the tubes faster because they are heavier. The biologists removed the clusters, transferred them to fresh media, and agitated them again.
Sixty cycles later, the clusters--now hundreds of cells--looked like spherical snowflakes.
Analysis showed that the clusters were not just groups of random cells that adhered to each other, but related cells that remained attached following cell division.
That was significant because it meant that they were genetically similar, which promotes cooperation. When the clusters reached a critical size, some cells died off in a process known as apoptosis to allow offspring to separate.
The offspring reproduced only after they attained the size of their parents.
"A cluster alone isn't multi-cellular," Ratcliff says. "But when cells in a cluster cooperate, make sacrifices for the common good, and adapt to change, that's an evolutionary transition to multi-cellularity."
In order for multi-cellular organisms to form, most cells need to sacrifice their ability to reproduce, an altruistic action that favors the whole but not the individual, Ratcliff says.
For example, all cells in the human body are essentially a support system that allows sperm and eggs to pass DNA along to the next generation.
Thus multi-cellularity is by its nature very cooperative.
"Some of the best competitors in nature are those that engage in cooperation, and our experiment bears that out," says Travisano.
Evolutionary biologists have estimated that multi-cellularity evolved independently in about 25 groups.
Travisano and Ratcliff wonder why it didn't evolve more often since it's not that difficult to recreate in a lab.
Considering that trillions of one-celled organisms lived on Earth for millions of years, it seems like it should have, Ratcliff says.
That may be a question the biologists will answer in the future using the fossil record for thousands of generations of multi-cellular clusters, which are stored in a freezer in Travisano's lab.
Since the frozen samples contain multiple cell lines that independently became multi-cellular, the researchers can compare them to learn whether similar or different mechanisms and genes were responsible in each case, Travisano says.
The next steps will be to look at the role of multi-cellularity in cancer, aging and other critical areas of biology.
"Multi-cellular yeast is a valuable resource for investigating a wide variety of medically and biologically important topics," Travisano says.
"Cancer was recently described as a fossil from the origin of multi-cellularity, which can be directly investigated with the yeast system.
"Similarly the origins of aging, development and the evolution of complex morphologies are open to direct experimental investigation that would otherwise be difficult or impossible."
-NSF-
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com