PROJECT SUMMARY The overall objective of research being pursued in the Delmore lab is to understand the genetics of behavior and speciation. Behavioral traits are tightly linked to fitness, human health, and disease but knowledge of their genetic basis is limited and has been hindered by several challenges, including their complexity (e.g., integration of many traits that are mediated by tissue-specific pathways) and limited expression in captive animal models. Similar gaps in our knowledge of speciation exist and relate to shortcomings in approaches used to identify reproductive isolation at the genomic level. Evolutionary processes involved in speciation (e.g., adaptation, admixture and genomic conflict) are important for understanding individual- and population-level patterns of human disease risk. The Delmore lab is using natural hybrid zones – areas where divergent populations interbreed – and recent advances in genomics to overcome challenges associated with studying the genetics of behavior and speciation. Recombination in hybrid zones isolates the effects of individual genetic loci, providing an entry point to identify genetic variants underlying behavioral variation exhibited by natural populations. Differences in behavior often help maintain species boundaries at hybrid zones, permitting simultaneous work on speciation genetics, including new approaches for estimating reproductive isolation. The Delmore lab has developed a migratory divide between songbirds as a model to understand the genetics of seasonal migratory behavior and speciation. Migratory divides are hybrid zones between populations that differ in several migratory traits (e.g., the timing and direction of migration). Migratory traits have a strong genetic basis and differences in these traits help maintain species boundaries. The Delmore lab recently established the infrastructure to quantify migratory traits reliably in both the field and lab. They can match these phenotypic data with information from multiple molecular levels and specific brain regions. This system will be leveraged to study the genetics of migration and speciation in the present proposal. An innovative multi-pronged approach will be used, integrating results from admixture mapping and population genomics in natural populations with laboratory examinations of gene regulation and functional analyses. By supplementing these results with comparative analyses, members of the Delmore lab will test the generality of their findings and continue identifying untapped avenues for future research. Together, these findings will provide unprecedented insight into genetic mechanisms that shape seasonal behavior and speciation and address several fundamental questions in evolutionary genetics, such as the role of pleiotropy in coordinating multiple traits, the sources and types of genetic variation underlying phenotypic traits, the contribution of multi-locus interactions to speciation, and whether molecular mechanisms ...