In the genomic era, it has become increasingly obvious that most traits that are relevant to the health, longevity, and fertility of organisms (including humans) are influenced by genetic variation (polymorphism). Despite intense interest in mapping and characterizing the responsible genes, the processes responsible for maintaining genetic variation are generally unknown. One reason is that direct experimental investigations are impossible in humans and difficult and expensive in most model organisms. More tractable species that can be studied in both natural and laboratory settings are needed to address this question. Wild guppies exhibit one of the most striking examples of polymorphism among animals (male color pattern variation), thought to be maintained by mating and survival advantages to rare or uncommon color types. Mating advantage appears result from female sexual responses to unusual males, and survival advantage appears to result from selective predation on common color types. This project will elucidate behavioral and genetic mechanisms underlying these patterns. Studies will examine (1) behavioral mechanisms leading to mating advantage for rare types, (2) behavioral responses of a predatory killifish to rare vs. common types and (3) brain gene expression changes that occur when guppies respond to novel sexual and environmental stimuli. Specific outcomes include determining (1) if female guppies have a specific preference for rare male types, (2) if prior experience with color types affects the predator's behavior and (3) which genes change their levels of expression in response to novel stimuli. This work will provide a clear picture of how behavioral and genetic processes contribute to genetic variation, and will also provide a model system for understanding response to novelty as a general phenomenon. Broader impacts of the project will include training of undergraduate and graduate students and further development of the guppy model system as a well-known exemplar for broad understanding of evolution.
