Social selection is a form of evolution that results from social competition, and acts on traits necessary for courtship, competition for resources and social dominance, and group behaviors. Artificial selection experiments that experimentally control social selection are a recent technique used to understand the genetic basis of behavior. While these experiments have revealed many traits under social selection, they have been limited to invertebrate groups. Moreover, research now indicates that organisms can respond to changes in the social environment via non-genomic epigenetic inheritance, where phenotypic responses to the environmental are transmitted to subsequent generations. This project addresses these gaps in our understanding by examining the behavioral, genetic, and epigenetic responses of laboratory-bred wild mice reintroduced to high population density and the opportunity for social selection. The prediction is that mice bred under laboratory conditions, where social selection is absent, down-regulate or eliminate costly traits that are only relevant during intense social selection. Data show that reintroduction of mice to a social environment rapidly increases male mating success but decreases survivorship in competitive environments, increases male signaling and attractiveness, and increases male expression of Major Urinary Proteins (MUPs), a primary signal in mouse communication. MUPs are known to be regulated by epigenetic inheritance, but the function remains unknown. This project now investigates the behavioral significance of increased MUP expression and the causal genetic and epigenetic mechanisms. It demonstrates how mammals respond to changes in the social environment, and will contribute to our understanding of behavioral ecology by showing how fitness and communication vary across social environments. It also will continue to engage undergraduate and high school students in scientific discovery by encouraging them to take independent roles in the research and to present their work at conferences.
