Advances in molecular technology make it possible to characterize the genetic basis of complex adaptations at levels of resolution that range from scanning the whole genome to identify regions that harbor genes associated with adaptations to pinpointing the contribution of individual genes to the evolution of specific features of the organism. Our project was designed at its inception to facilitate the use of these tools for characterizing how guppies adapt to life with and without predators. Our potential to do so lies in our having created an episode of selection by transplanting guppies from a site where they are adapted to life with predators and the associated elevated risk of mortality to sites were predators are absent and life expectancy is considerably extended. This experiment was done with four-fold replication. As part of our monthly mark-recapture censuses we are able to mark and collect scales from >99% of the fish that attain maturity in each stream. The scales in turn serve as a source of DNA that we are using to reconstruct the pedigree, which means that we can quantify how many offspring each fish contributes to the next generation. Our being able to do so means that we have our fingers on the pulse of evolution because we can relate each individual’s reproductive success to whatever attributes it has that fostered that success. We only use 20% of the available DNA for the pedigree, which means that we also have an archive of DNA from almost every individual for use in subsequent studies of the genetics of adaptation. In addition to our four experimental streams, there were three earlier transplants of guppies from high to low predation environments that date to 1957, 1976 and 1981. These provide us with additional replication plus a longer time line for characterizing evolution.
The catalog of known differences between guppies adapted to these alternative environments displays the potential range of traits that could become available for study. Guppies from these two sites differ in the age and size at maturity, the number and size of offspring, the rate of aging and life expectancy, behavior, male coloration, body shape, growth rate, neuromuscular performance and metabolic rate. There is the potential for all of these traits to become accessible to genetic analysis. We note that all of these traits are of interest in basic science, but some of them (e.g., aging and neuromuscular performance) are of interest in biomedical sciences.
Considerable progress has been made in establishing guppies as a model for studying the genetics of adaptation. There is now a high quality published genome sequence for the population of guppies that serves as the founders of our four new introduction experiments. Investigators have developed a optimized, low cost, high throughput genotyping protocol using RADseq. This protocol has already been applied to a range of natural populations and has identified some regions of the genome that likely contain genes associated with adaptation to life with and without predators We have completed a quantitative trait locus experimental cross, which creates the raw material for identifying regions of the genome that contain genes that make large contributions to the trait under consideration, which in our case is the age and size at maturity in male guppies. While we have yet to obtain large-scale funding for this aspect of our research, we are making significant progress in creating a unique resource for studying evolution in action and the underlying genetic causes of that evolution.
The catalog of known differences between guppies adapted to these alternative environments displays the potential range of traits that could become available for study. Guppies from these two sites differ in the age and size at maturity, the number and size of offspring, the rate of aging and life expectancy, behavior, male coloration, body shape, growth rate, neuromuscular performance and metabolic rate. There is the potential for all of these traits to become accessible to genetic analysis. We note that all of these traits are of interest in basic science, but some of them (e.g., aging and neuromuscular performance) are of interest in biomedical sciences.
Considerable progress has been made in establishing guppies as a model for studying the genetics of adaptation. There is now a high quality published genome sequence for the population of guppies that serves as the founders of our four new introduction experiments. Investigators have developed a optimized, low cost, high throughput genotyping protocol using RADseq. This protocol has already been applied to a range of natural populations and has identified some regions of the genome that likely contain genes associated with adaptation to life with and without predators We have completed a quantitative trait locus experimental cross, which creates the raw material for identifying regions of the genome that contain genes that make large contributions to the trait under consideration, which in our case is the age and size at maturity in male guppies. While we have yet to obtain large-scale funding for this aspect of our research, we are making significant progress in creating a unique resource for studying evolution in action and the underlying genetic causes of that evolution.
