ScienceDaily (Nov. 22, 2010) — Since 1871, when Charles Darwin wrote The Descent of Man, it has been widely accepted that "Variability is the necessary basis for the action of selection." Variability is associated with the ability to adapt, which is clearly beneficial at a species level. But there is increasing evidence that genetic variability may also give rise to advantages at the level of the individual. Steve Smith and Franz Suchentrunk at the Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna have now shown that variation at a particular gene locus in hares is associated with greater reproductive success.
The results are published in the October issue of the journal Molecular Ecology.
One of the key questions of evolutionary biology is how variation at the level of single genes affects animals' ability to produce young. Together with collaborators in the UK and in Belgium, Steve Smith and Franz Suchentrunk at the Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna have designed a mathematical model to describe the effects of genetic variation on the reproductive success of the European hare. They tested the model on data obtained from wild hares in Belgium and in eastern Austria.
Smith and colleagues elected to examine the influence of two different sites in the major histocompatability complex (MHC). The MHC is involved in immune reactions and MHC genes have recently received a great deal of attention as representing a possible link between genetic variation and fitness. A number of studies have implicated them as possible causes of reproductive failure in humans but to date no experiments have attempted to assess whether MHC genes are associated with fitness in populations of wild animals.
Reproductive success results from a combination of two factors: fertility (whether an individual produces young) and fecundity (how many young are produced per fertile individual). Smith and colleagues have now found that females that carry two different versions of a particular MHC locus (i.e. that are are heterozygous at this locus) have a sigificantly higher reproductive success than homozygous females. The scientists observed a marked reduction in sterility in heterozygous hares, together with a slight but detectable increase in fecundity. Their results confirm for the first time that variability at a particular genetic locus is associated with reproductive performance and have extremely important consequences for studies on human fertility as well as for wildlife management.
Intriguingly, although the positive effects of heterozygosity could be clearly detected in hares from Belgium they were not found in hares from eastern Austria. The difference presumably stems from different selection pressures on the two populations. For example, the annual range of termperature is significantly wider in Austria than in Belgium, so hares in Austria may be subjected to greater fluctuations in the availability of food. As Smith says, though, "the difference between Austria and Belgium shows just how complicated the whole question is and thus how hard it is to extrapolate results from one system to another."
http://www.sciencedaily.com/releases/2010/11/101122093106.htm
Showing posts with label asexual reproduction. Show all posts
Showing posts with label asexual reproduction. Show all posts
Tuesday, November 23, 2010
Spice of Life: Variety Is Also Good for Hares
ScienceDaily (Nov. 22, 2010) — Since 1871, when Charles Darwin wrote The Descent of Man, it has been widely accepted that "Variability is the necessary basis for the action of selection." Variability is associated with the ability to adapt, which is clearly beneficial at a species level. But there is increasing evidence that genetic variability may also give rise to advantages at the level of the individual. Steve Smith and Franz Suchentrunk at the Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna have now shown that variation at a particular gene locus in hares is associated with greater reproductive success.
The results are published in the October issue of the journal Molecular Ecology.
One of the key questions of evolutionary biology is how variation at the level of single genes affects animals' ability to produce young. Together with collaborators in the UK and in Belgium, Steve Smith and Franz Suchentrunk at the Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna have designed a mathematical model to describe the effects of genetic variation on the reproductive success of the European hare. They tested the model on data obtained from wild hares in Belgium and in eastern Austria.
Smith and colleagues elected to examine the influence of two different sites in the major histocompatability complex (MHC). The MHC is involved in immune reactions and MHC genes have recently received a great deal of attention as representing a possible link between genetic variation and fitness. A number of studies have implicated them as possible causes of reproductive failure in humans but to date no experiments have attempted to assess whether MHC genes are associated with fitness in populations of wild animals.
Reproductive success results from a combination of two factors: fertility (whether an individual produces young) and fecundity (how many young are produced per fertile individual). Smith and colleagues have now found that females that carry two different versions of a particular MHC locus (i.e. that are are heterozygous at this locus) have a sigificantly higher reproductive success than homozygous females. The scientists observed a marked reduction in sterility in heterozygous hares, together with a slight but detectable increase in fecundity. Their results confirm for the first time that variability at a particular genetic locus is associated with reproductive performance and have extremely important consequences for studies on human fertility as well as for wildlife management.
Intriguingly, although the positive effects of heterozygosity could be clearly detected in hares from Belgium they were not found in hares from eastern Austria. The difference presumably stems from different selection pressures on the two populations. For example, the annual range of termperature is significantly wider in Austria than in Belgium, so hares in Austria may be subjected to greater fluctuations in the availability of food. As Smith says, though, "the difference between Austria and Belgium shows just how complicated the whole question is and thus how hard it is to extrapolate results from one system to another."
http://www.sciencedaily.com/releases/2010/11/101122093106.htm
The results are published in the October issue of the journal Molecular Ecology.
One of the key questions of evolutionary biology is how variation at the level of single genes affects animals' ability to produce young. Together with collaborators in the UK and in Belgium, Steve Smith and Franz Suchentrunk at the Research Institute of Wildlife Ecology, University of Veterinary Medicine, Vienna have designed a mathematical model to describe the effects of genetic variation on the reproductive success of the European hare. They tested the model on data obtained from wild hares in Belgium and in eastern Austria.
Smith and colleagues elected to examine the influence of two different sites in the major histocompatability complex (MHC). The MHC is involved in immune reactions and MHC genes have recently received a great deal of attention as representing a possible link between genetic variation and fitness. A number of studies have implicated them as possible causes of reproductive failure in humans but to date no experiments have attempted to assess whether MHC genes are associated with fitness in populations of wild animals.
Reproductive success results from a combination of two factors: fertility (whether an individual produces young) and fecundity (how many young are produced per fertile individual). Smith and colleagues have now found that females that carry two different versions of a particular MHC locus (i.e. that are are heterozygous at this locus) have a sigificantly higher reproductive success than homozygous females. The scientists observed a marked reduction in sterility in heterozygous hares, together with a slight but detectable increase in fecundity. Their results confirm for the first time that variability at a particular genetic locus is associated with reproductive performance and have extremely important consequences for studies on human fertility as well as for wildlife management.
Intriguingly, although the positive effects of heterozygosity could be clearly detected in hares from Belgium they were not found in hares from eastern Austria. The difference presumably stems from different selection pressures on the two populations. For example, the annual range of termperature is significantly wider in Austria than in Belgium, so hares in Austria may be subjected to greater fluctuations in the availability of food. As Smith says, though, "the difference between Austria and Belgium shows just how complicated the whole question is and thus how hard it is to extrapolate results from one system to another."
http://www.sciencedaily.com/releases/2010/11/101122093106.htm
Friday, November 5, 2010
Boa Constrictors Can Have Babies Without Mating, New Evidence Shows
ScienceDaily (Nov. 4, 2010) — In a finding that upends decades of scientific theory on reptile reproduction, researchers at North Carolina State University have discovered that female boa constrictors can squeeze out babies without mating.
More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible.
Large litters of all-female babies produced by the "super mom" boa constrictor show absolutely no male influence -- no genetic fingerprint that a male was involved in the reproductive process. All the female babies also retained their mother's rare recessive color mutation.
This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.
The study is published online in Biology Letters, a Royal Society journal.
Snake sex chromosomes are a bit different from those in mammals -- male snakes' cells have two Z chromosomes, while female snakes' cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced -- and even then only in fish and amphibians, Booth says.
Adding to the oddity is the fact that within two years, the same boa mother produced not one, but two different snake broods of all-female, WW-chromosome babies that had the mother's rare color mutation. One brood contained 12 babies and the second contained 10 babies. And it wasn't because she lacked options: Male snakes were present and courted the female before she gave birth to the rare babies. And the versatile super-mom had previously had babies the "old-fashioned way" by mating with a male well before her two asexual reproduction experiences.
Booth doubts that the rare births were caused by environmental changes. He notes that while environmental stresses have been associated with asexual reproduction in some fish and other animals, no changes occurred in the mother boa's environment or routine.
It's possible that this one snake is some sort of genetic freak of nature, but Booth says that asexual reproduction in snakes could be more common than people think.
"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."
A reptile keeper and snake breeder, Booth now owns one of the young females from the study. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or -- like their mother -- do both. In any case, these WW-chromosomed females will continue their version of "girl power," as any baby they produce will also be female.
Drs. Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. NC State's Department of Entomology is part of the university's College of Agriculture and Life Sciences.
http://www.sciencedaily.com/releases/2010/11/101103111210.htm
More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible.
Large litters of all-female babies produced by the "super mom" boa constrictor show absolutely no male influence -- no genetic fingerprint that a male was involved in the reproductive process. All the female babies also retained their mother's rare recessive color mutation.
This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.
The study is published online in Biology Letters, a Royal Society journal.
Snake sex chromosomes are a bit different from those in mammals -- male snakes' cells have two Z chromosomes, while female snakes' cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced -- and even then only in fish and amphibians, Booth says.
Adding to the oddity is the fact that within two years, the same boa mother produced not one, but two different snake broods of all-female, WW-chromosome babies that had the mother's rare color mutation. One brood contained 12 babies and the second contained 10 babies. And it wasn't because she lacked options: Male snakes were present and courted the female before she gave birth to the rare babies. And the versatile super-mom had previously had babies the "old-fashioned way" by mating with a male well before her two asexual reproduction experiences.
Booth doubts that the rare births were caused by environmental changes. He notes that while environmental stresses have been associated with asexual reproduction in some fish and other animals, no changes occurred in the mother boa's environment or routine.
It's possible that this one snake is some sort of genetic freak of nature, but Booth says that asexual reproduction in snakes could be more common than people think.
"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."
A reptile keeper and snake breeder, Booth now owns one of the young females from the study. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or -- like their mother -- do both. In any case, these WW-chromosomed females will continue their version of "girl power," as any baby they produce will also be female.
Drs. Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. NC State's Department of Entomology is part of the university's College of Agriculture and Life Sciences.
http://www.sciencedaily.com/releases/2010/11/101103111210.htm
Boa Constrictors Can Have Babies Without Mating, New Evidence Shows
ScienceDaily (Nov. 4, 2010) — In a finding that upends decades of scientific theory on reptile reproduction, researchers at North Carolina State University have discovered that female boa constrictors can squeeze out babies without mating.
More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible.
Large litters of all-female babies produced by the "super mom" boa constrictor show absolutely no male influence -- no genetic fingerprint that a male was involved in the reproductive process. All the female babies also retained their mother's rare recessive color mutation.
This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.
The study is published online in Biology Letters, a Royal Society journal.
Snake sex chromosomes are a bit different from those in mammals -- male snakes' cells have two Z chromosomes, while female snakes' cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced -- and even then only in fish and amphibians, Booth says.
Adding to the oddity is the fact that within two years, the same boa mother produced not one, but two different snake broods of all-female, WW-chromosome babies that had the mother's rare color mutation. One brood contained 12 babies and the second contained 10 babies. And it wasn't because she lacked options: Male snakes were present and courted the female before she gave birth to the rare babies. And the versatile super-mom had previously had babies the "old-fashioned way" by mating with a male well before her two asexual reproduction experiences.
Booth doubts that the rare births were caused by environmental changes. He notes that while environmental stresses have been associated with asexual reproduction in some fish and other animals, no changes occurred in the mother boa's environment or routine.
It's possible that this one snake is some sort of genetic freak of nature, but Booth says that asexual reproduction in snakes could be more common than people think.
"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."
A reptile keeper and snake breeder, Booth now owns one of the young females from the study. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or -- like their mother -- do both. In any case, these WW-chromosomed females will continue their version of "girl power," as any baby they produce will also be female.
Drs. Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. NC State's Department of Entomology is part of the university's College of Agriculture and Life Sciences.
http://www.sciencedaily.com/releases/2010/11/101103111210.htm
More strikingly, the finding shows that the babies produced from this asexual reproduction have attributes previously believed to be impossible.
Large litters of all-female babies produced by the "super mom" boa constrictor show absolutely no male influence -- no genetic fingerprint that a male was involved in the reproductive process. All the female babies also retained their mother's rare recessive color mutation.
This is the first time asexual reproduction, known in the scientific world as parthenogenesis, has been attributed to boa constrictors, says Dr. Warren Booth, an NC State postdoctoral researcher in entomology and the lead author of a paper describing the study. He adds that the results may force scientists to re-examine reptile reproduction, especially among more primitive snake species like boa constrictors.
The study is published online in Biology Letters, a Royal Society journal.
Snake sex chromosomes are a bit different from those in mammals -- male snakes' cells have two Z chromosomes, while female snakes' cells have a Z and a W chromosome. Yet in the study, all the female babies produced by asexual reproduction had WW chromosomes, a phenomenon Booth says had not been seen before and was believed to be impossible. Only through complex manipulation in lab settings could such WW females be produced -- and even then only in fish and amphibians, Booth says.
Adding to the oddity is the fact that within two years, the same boa mother produced not one, but two different snake broods of all-female, WW-chromosome babies that had the mother's rare color mutation. One brood contained 12 babies and the second contained 10 babies. And it wasn't because she lacked options: Male snakes were present and courted the female before she gave birth to the rare babies. And the versatile super-mom had previously had babies the "old-fashioned way" by mating with a male well before her two asexual reproduction experiences.
Booth doubts that the rare births were caused by environmental changes. He notes that while environmental stresses have been associated with asexual reproduction in some fish and other animals, no changes occurred in the mother boa's environment or routine.
It's possible that this one snake is some sort of genetic freak of nature, but Booth says that asexual reproduction in snakes could be more common than people think.
"Reproducing both ways could be an evolutionary 'get-out-of-jail-free card' for snakes," Booth says. "If suitable males are absent, why waste those expensive eggs when you have the potential to put out some half-clones of yourself? Then, when a suitable mate is available, revert back to sexual reproduction."
A reptile keeper and snake breeder, Booth now owns one of the young females from the study. When the all-female snake babies reach sexual maturity in a few years, Booth will be interested to see if they mate with a male, produce babies without a mate, or -- like their mother -- do both. In any case, these WW-chromosomed females will continue their version of "girl power," as any baby they produce will also be female.
Drs. Coby Schal and Ed Vargo co-authored the paper. Co-author Sharon Moore raised the snakes in the study. Co-author and veterinarian Daniel Johnson provided surgical sex testing on the snakes. NC State's Department of Entomology is part of the university's College of Agriculture and Life Sciences.
http://www.sciencedaily.com/releases/2010/11/101103111210.htm
Subscribe to:
Posts (Atom)