Genetic leakage after adaptive and nonadaptive divergence in the Ensatina eschscholtzii ring species.

The salamander Ensatina eschscholtzii is an example of a ring species in which extant intermediate stages of terminal forms have a nearly continuous range, offering replicated interactions at several stages of divergence. We employ a greatly expanded allozyme database and individual-based analyses to separate the effects of divergence time and gene flow to evaluate how gradual divergence of populations around the ring contributes to the development of reproductive isolation. Despite the high degree of genetic (D8 km). Diversification and consequent genetic interactions in Ensatina reveal a continuum between populations, ecological races, and species, where polytypic traits and high genetic differentiation are maintained without reproductive isolation.