DISSERTATION RESEARCH: Hybridization, selection, and adaptive divergence between two bird species distributed along an environmental gradient

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The two species of marsh birds being studied live along the Gulf and Atlantic coasts. King Rails breed in freshwater marshes, while the very similar Clapper Rail breeds in saltmarshes, and the two hybridize in intermediate brackish marshes. The researchers collected and genetically analyzed birds distributed along the transition from freshwater to saltwater in Louisiana, and found evidence that adaptation to the environment may be keeping the two species from fusing into one. The goal of the funded NSF project is to find the genes underlying this adaptation and analyze them for the samples collected across the transition. The researchers will use next-generation sequencing technologies to gather large amounts of genetic data on samples already collected, and try to understand adaptation in the context of this hybrid zone. The overall goal of the research is to better understand the process of speciation. The researchers are interested in using closely related species that are hybridizing to understand the forces maintaining the distinct species. Their long-term goal with the rails is to understand genetic differences between the two species that underlie adaptations to different salinities. The results of this study will provide the most detailed population genetic analysis of two closely related, hybridizing species of birds to date. Additionally, this will be the first genetic characterization of the avian salt gland, a specialized salt-excreting organ found in some birds. Finally, the results will provide a foundation for a multitude of future research studies of this system.