This proposal will trace the history and mechanisms of divergence in a textbook example of speciation, salamanders of the Ensatina eschscholtzii complex of western North America, to further understanding of how new species are formed. The investigators will test hypotheses about the evolutionary processes that have shaped patterns of geographic variation using DNA sequence data at a broad scale, in concert with highly variable DNA microsatellites to scrutinize interactions between individuals at contact zones between differentiated populations. Controlled mating experiments will be used to test hypotheses about the origin and maintenance of reproductive isolating barriers to elucidate how species remain distinct from other, closely related species where they cooccur.
Ensatina salamanders represent one of only two known cases of a ring species. Ring species have been called the perfect demonstration of speciation because we can trace the history of divergence through the intermediate forms connecting the two terminal parts of a continuum of populations that act as distinct species. Results will be communicated to the scientific community via publication in journals, and directly to the public via the award winning Understanding Evolution website, developed and maintained by UC Berkeley which provides evolution education resources to teachers and students.
