The role of adaptation in shaping phenotypic variation within and among closely related populations is a central theme in my research program. As an evolutionary ecologist, I am interested in the biological causes and consequences of variation in phenotype using molecular, comparative, and experimental methods. By adopting new comparative approaches (both empirical and synthetic), my current work is focused on determining how trait function affects patterns of gene flow. We are currently establishing new methods to test hypotheses about the relative contributions of geographic distance, history, natural and sexual selection in the evolution of reproductive isolation.