Effects of holocene climate fluctuation on mitochondrial DNA variation in the ringed salamander, Ambystoma annulatum

We analyzed mitochondrial DNA variation in the Ringed Salamander, Ambystoma annulatum, Four of six populations studied were fixed for the same haploty pe. We attribute this: lack of detectable variation to recent colonization of this area, a hypothesis which is supported by paleoecological data and p revious biogeographical analysis of the sympatric Spotted Salamander, Ambys toma,maculatum. This study demonstrates the potential benefits of comparing biogeographical data across species and suggests that the Hypsithermal Int erval may be an overlooked source of important historical impacts for speci es in the midwestern United States.