Central to evolutionary biology is understanding how reproductive isolation between two closely related species develops. This study uses two swallowtail butterfly species, Papilio glaucus and Papilio canadensis, as a system to study the genetic basis of reproductive isolation between newly emerging species. The two species differ in many ecological traits that are linked to their sex chromosomes, yet where their ranges meet they are still capable of forming fertile hybrids. The investigators predict that some genes are able to move through the hybrid zone, while genes linked to species-specific ecologically important traits do not. Implementing both standard and novel population genetic approaches, thirty sex-linked genes will be examined in parental and hybrid populations of P. glaucus and P. canadensis to test the prediction. Using parental populations, the study will also elucidate which sex-linked traits were important in the initial divergence of the two species.
The Papilio hybrid zone is a well-known geographic hotspot for species turnover and hybridization in many plants and animals in North America. Insights gained by the proposed research will improve our understanding of complex ecological systems. This study will significantly contribute to genetic resources for non-model organisms. In addition, publicly available software will be developed that can be applied to many biological species.
