ScienceDaily (Dec. 29, 2010) — New research on lizards in the Caribbean demonstrates that species diversification is limited by the environment. The finding supports and extends the MacArthur-Wilson theory of island biogeography.
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
Showing posts with label dna sequence. Show all posts
Showing posts with label dna sequence. Show all posts
Thursday, December 30, 2010
Environmental Factors Limit Species Diversity, Lizard Study Finds
ScienceDaily (Dec. 29, 2010) — New research on lizards in the Caribbean demonstrates that species diversification is limited by the environment. The finding supports and extends the MacArthur-Wilson theory of island biogeography.
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
It's long been accepted by biologists that environmental factors cause the diversity -- or number -- of species to increase before eventually leveling off. Some recent work, however, has suggested that species diversity continues instead of entering into a state of equilibrium. But new research on lizards in the Caribbean not only supports the original theory that finite space, limited food supplies, and competition for resources all work together to achieve equilibrium; it builds on the theory by extending it over a much longer timespan.
The research was done by Daniel Rabosky of the University of California, Berkeley and Richard Glor of the University of Rochester who studied patterns of species accumulation of lizards over millions of years on the four Caribbean islands of Puerto Rico, Jamaica, Hispaniola, and Cuba. Their paper is being published December 21 in the journal, Proceedings of the National Academy of Sciences.
Glor and Rabosky focused on species diversity -- the number of distinct species of lizards -- not the number of individual lizards.
"Geographic size correlates to diversity," said Glor. "In general, the larger the area, the greater the number of species that can be supported. For example, there are 60 species of Anolis lizards on Cuba, but far fewer species on the much smaller islands of Jamaica and Puerto Rico." There are only 6 species on Jamaica and 10 on Puerto Rico.
Ecologists Robert MacArthur of Princeton University and E.O. Wilson of Harvard University established the theory of island biogeography in the 1960s to explain the diversity and richness of species in restricted habitats, as well as the limits on the growth in number of species. Glor said the MacArthur-Wilson theory was developed for ecological time-scales, which encompass thousands of years, while his work with Rabosky extends the concepts over a million years. "MacArthur and Wilson recognized the macroevolutionary implications of their work," explained Glor, "but focused on ecological time-scales for simplicity."
Historically, biologists needed fossil records to study patterns of species diversification of lizards on the Caribbean islands. But advances in molecular methodology allowed Glor and Rabosky to use DNA sequences to reconstruct evolutionary trees that show the relationships between species.
The two scientists found that species diversification of lizards on the four islands reached a plateau millions of years ago and has essentially come to an end.
Glor said the extent and quality of the data used in the research allowed him and Rabosky to show that species diversification of lizards on the islands was not continuing and had indeed entered a state of equilibrium.
"When we look at other islands and continents that vary in species richness," said Glor, "we can't just consider rates of accumulation; we need to look at the plateau points."
Glor emphasizes that a state of equilibrium does not mean that the evolution of a species comes to an end. Lizards will continue to adapt to changes in their environment, but they are not expected to develop in a way that increases the number of species within a habitat.
Glor believes his work with Rabosky represents the "final word" on the importance of limits on species diversity over the rate of speciation when explaining the species-area relationship in anole lizards.
http://www.sciencedaily.com/releases/2010/12/101220163248.htm
Saturday, November 27, 2010
Animal genomes riddled with the 'skeletons' of ancient viruses
It’s time for animals - including humans - to admit that the bacteria, viruses and other microbes have won. Our bodies are home to many times more bacterial cells than animal cells and countless trillions of viruses. Ancient retroviruses make up a good size chunk of our genome. Now, scientists have discovered that most any virus can set up shop in an animal's genomes and lay dormant for millions of years.
A scan of 44 mammal genomes, plus those of several mosquito and tick vectors and two birds that could serve as reservoirs, has uncovered DNA sequences that can be traced to 10 different families of viruses, including some related to viruses that cause hepatitis B, Ebola, rabies and dengue. Most of the viral sequences are riddled with enough mutations to be considered junk, but some appear to encoding working genes co-opted by their host. The work is published online today in the journal PLoS Genetics.
It’s not obvious how all these viruses got into animal genomes. The researchers, Aris Katzourakis at the University of Oxford, UK, and Robert Gifford at Rockefeller University in New York, searched specifically for viruses that aren’t retroviruses, which are obligated to copy their DNA into hosts. Many but not all of the viruses infect their hosts persistently or replicate inside of the nucleus, however, offering ample opportunity to take up residence in the genomes of germ cells.
The work is just a first look at all the non-retroviruses in the animal genome, but Katzourakis and Gifford turned up a few interesting findings. For instance, their scan identified sequences from filoviruses, the family Ebola belongs to, in the genomes of bats, tarsiers, several rodents, opossums and even wallabies. This hints that filoviruses have a much wider host range than the primate and bat species which these viruses are known to infect.
The paper also hints at unknown ancient transmissions of viruses between hosts. The bottlenose dolphin genome, it turns out, is home to sequences of a kind of parvovirus similar to one found in birds, suggesting that the viruses may have jumped between mammals and birds in the past.
Most of these sequences are junk, so filled with mutations that they can’t make working proteins. But some of the viral sequences might do something inside their hosts. One example is a bornavirus gene called EBLN-1 that took up residence in ancient primate genomes some 50 million years ago and survives intact in many modern primates, including humans. A similar protein latches onto RNA in bornaviruses, so it might do the same in primates as part of a viral defence mechanism, Gifford speculates.
Like the ancient retroviruses locked inside animal genomes, these viruses offer a window into infections that occurred millions of years ago.
“People who are looking at the ecology of those diseases, they very much work in recent time and they have no assumptions that it’s an old system that might have evolved over billions of years,” says Gifford. "The data that we’re finding is really contradicting that and providing the first evidence that these are really old relationships between hosts and viruses, and I think it’s really critical to how we underestand them to get that context right."
A scan of 44 mammal genomes, plus those of several mosquito and tick vectors and two birds that could serve as reservoirs, has uncovered DNA sequences that can be traced to 10 different families of viruses, including some related to viruses that cause hepatitis B, Ebola, rabies and dengue. Most of the viral sequences are riddled with enough mutations to be considered junk, but some appear to encoding working genes co-opted by their host. The work is published online today in the journal PLoS Genetics.
It’s not obvious how all these viruses got into animal genomes. The researchers, Aris Katzourakis at the University of Oxford, UK, and Robert Gifford at Rockefeller University in New York, searched specifically for viruses that aren’t retroviruses, which are obligated to copy their DNA into hosts. Many but not all of the viruses infect their hosts persistently or replicate inside of the nucleus, however, offering ample opportunity to take up residence in the genomes of germ cells.
The work is just a first look at all the non-retroviruses in the animal genome, but Katzourakis and Gifford turned up a few interesting findings. For instance, their scan identified sequences from filoviruses, the family Ebola belongs to, in the genomes of bats, tarsiers, several rodents, opossums and even wallabies. This hints that filoviruses have a much wider host range than the primate and bat species which these viruses are known to infect.
The paper also hints at unknown ancient transmissions of viruses between hosts. The bottlenose dolphin genome, it turns out, is home to sequences of a kind of parvovirus similar to one found in birds, suggesting that the viruses may have jumped between mammals and birds in the past.
Most of these sequences are junk, so filled with mutations that they can’t make working proteins. But some of the viral sequences might do something inside their hosts. One example is a bornavirus gene called EBLN-1 that took up residence in ancient primate genomes some 50 million years ago and survives intact in many modern primates, including humans. A similar protein latches onto RNA in bornaviruses, so it might do the same in primates as part of a viral defence mechanism, Gifford speculates.
Like the ancient retroviruses locked inside animal genomes, these viruses offer a window into infections that occurred millions of years ago.
“People who are looking at the ecology of those diseases, they very much work in recent time and they have no assumptions that it’s an old system that might have evolved over billions of years,” says Gifford. "The data that we’re finding is really contradicting that and providing the first evidence that these are really old relationships between hosts and viruses, and I think it’s really critical to how we underestand them to get that context right."
Animal genomes riddled with the 'skeletons' of ancient viruses
It’s time for animals - including humans - to admit that the bacteria, viruses and other microbes have won. Our bodies are home to many times more bacterial cells than animal cells and countless trillions of viruses. Ancient retroviruses make up a good size chunk of our genome. Now, scientists have discovered that most any virus can set up shop in an animal's genomes and lay dormant for millions of years.
A scan of 44 mammal genomes, plus those of several mosquito and tick vectors and two birds that could serve as reservoirs, has uncovered DNA sequences that can be traced to 10 different families of viruses, including some related to viruses that cause hepatitis B, Ebola, rabies and dengue. Most of the viral sequences are riddled with enough mutations to be considered junk, but some appear to encoding working genes co-opted by their host. The work is published online today in the journal PLoS Genetics.
It’s not obvious how all these viruses got into animal genomes. The researchers, Aris Katzourakis at the University of Oxford, UK, and Robert Gifford at Rockefeller University in New York, searched specifically for viruses that aren’t retroviruses, which are obligated to copy their DNA into hosts. Many but not all of the viruses infect their hosts persistently or replicate inside of the nucleus, however, offering ample opportunity to take up residence in the genomes of germ cells.
The work is just a first look at all the non-retroviruses in the animal genome, but Katzourakis and Gifford turned up a few interesting findings. For instance, their scan identified sequences from filoviruses, the family Ebola belongs to, in the genomes of bats, tarsiers, several rodents, opossums and even wallabies. This hints that filoviruses have a much wider host range than the primate and bat species which these viruses are known to infect.
The paper also hints at unknown ancient transmissions of viruses between hosts. The bottlenose dolphin genome, it turns out, is home to sequences of a kind of parvovirus similar to one found in birds, suggesting that the viruses may have jumped between mammals and birds in the past.
Most of these sequences are junk, so filled with mutations that they can’t make working proteins. But some of the viral sequences might do something inside their hosts. One example is a bornavirus gene called EBLN-1 that took up residence in ancient primate genomes some 50 million years ago and survives intact in many modern primates, including humans. A similar protein latches onto RNA in bornaviruses, so it might do the same in primates as part of a viral defence mechanism, Gifford speculates.
Like the ancient retroviruses locked inside animal genomes, these viruses offer a window into infections that occurred millions of years ago.
“People who are looking at the ecology of those diseases, they very much work in recent time and they have no assumptions that it’s an old system that might have evolved over billions of years,” says Gifford. "The data that we’re finding is really contradicting that and providing the first evidence that these are really old relationships between hosts and viruses, and I think it’s really critical to how we underestand them to get that context right."
A scan of 44 mammal genomes, plus those of several mosquito and tick vectors and two birds that could serve as reservoirs, has uncovered DNA sequences that can be traced to 10 different families of viruses, including some related to viruses that cause hepatitis B, Ebola, rabies and dengue. Most of the viral sequences are riddled with enough mutations to be considered junk, but some appear to encoding working genes co-opted by their host. The work is published online today in the journal PLoS Genetics.
It’s not obvious how all these viruses got into animal genomes. The researchers, Aris Katzourakis at the University of Oxford, UK, and Robert Gifford at Rockefeller University in New York, searched specifically for viruses that aren’t retroviruses, which are obligated to copy their DNA into hosts. Many but not all of the viruses infect their hosts persistently or replicate inside of the nucleus, however, offering ample opportunity to take up residence in the genomes of germ cells.
The work is just a first look at all the non-retroviruses in the animal genome, but Katzourakis and Gifford turned up a few interesting findings. For instance, their scan identified sequences from filoviruses, the family Ebola belongs to, in the genomes of bats, tarsiers, several rodents, opossums and even wallabies. This hints that filoviruses have a much wider host range than the primate and bat species which these viruses are known to infect.
The paper also hints at unknown ancient transmissions of viruses between hosts. The bottlenose dolphin genome, it turns out, is home to sequences of a kind of parvovirus similar to one found in birds, suggesting that the viruses may have jumped between mammals and birds in the past.
Most of these sequences are junk, so filled with mutations that they can’t make working proteins. But some of the viral sequences might do something inside their hosts. One example is a bornavirus gene called EBLN-1 that took up residence in ancient primate genomes some 50 million years ago and survives intact in many modern primates, including humans. A similar protein latches onto RNA in bornaviruses, so it might do the same in primates as part of a viral defence mechanism, Gifford speculates.
Like the ancient retroviruses locked inside animal genomes, these viruses offer a window into infections that occurred millions of years ago.
“People who are looking at the ecology of those diseases, they very much work in recent time and they have no assumptions that it’s an old system that might have evolved over billions of years,” says Gifford. "The data that we’re finding is really contradicting that and providing the first evidence that these are really old relationships between hosts and viruses, and I think it’s really critical to how we underestand them to get that context right."
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