The evolutionary genetics of reinforcement: an empirical study in neotropical Costus

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Understanding the role that natural selection plays in the origin of species is a central goal of evolutionary biology. Population genetics theory shows that, in special circumstances, natural selection can reinforce reproductive barriers between recently diverged species living in the same geographic area, but this theory has not been adequately addressed with data from natural systems. This project examines the evolutionary genetics of this process in a rapidly speciating group of tropical plants for which prior research has found evidence of reinforcement of reproductive barriers. The research uses genetic mapping techniques to characterize the genetic basis of the traits and mechanisms that reproductively isolate two recently diverged species, field experiments to better understand the ecological consequences of those traits, and molecular markers to assess historical patterns of gene flow between the species.The idea that natural selection can directly favor speciation is important, because it shows a direct link between the processes of adaptation and speciation and because it elucidates a route for diversification to occur without prolonged periods of geographic isolation. This research empirically addresses the circumstances under which selection can reinforce speciation in a comprehensive way that links ecological factors and the underlying genetic processes. The results will be broadly applicable to understanding how certain groups of organisms and geographic areas have diversified without long periods of time or geographic isolation. The project will train young scientists in molecular genetics and evolution, and provide opportunities for them to conduct field research in a tropical rainforest.