Dissertation Research: An investigation of isolating mechanisms between sister species in the genus Empidonax

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Examination of the processes involved in the formation of new species remains an active area of investigation in evolutionary biology. New species form when barriers to the exchange of genes arise between groups of organisms. The strength of specific types of barriers can be tested when closely related species interact in areas of geographic overlap. This project examines the strength of two important potential barriers to genetic exchange between two closely related North American songbirds. Pacific-slope flycatchers and Cordilleran flycatchers differ in habitat preference across much of their ranges and differ in song, a trait important in mate choice. They co-occur in two areas. In one area, genetic exchange is relatively common, whereas in the other it is restricted. By combining GIS-based bioclimatic analysis and experimental tests of mating behavior with genetic analysis, this study will examine the effects of differences in habitat preference and mating behavior on the exchange of genes. This study utilizes an integrated approach to investigate key processes involved in the formation of new species. The existence of two areas of geographic contact with differing evolutionary dynamics presents a unique opportunity to compare the relative strengths of different barriers to gene exchange. Understanding the factors that regulate the exchange of genes between closely related species has important conservation implications, as research has demonstrated potentially negative consequences of genetic exchange between rare or threatened species and close relatives. Outreach activities will involve K-12 students and undergraduates will be mentored as part of the research plan.