Allozyme analysis of a contact zone between two mtDNA haplotypes in Desmognathus ocoee (Amphibia: Plethodontidae)

Recent phylogenetic analyses of mitochondrial DNA (mtDNA) sequences have revealed five distinct, well supported clades within the salamander species traditionally called Desmongnathus ocoee Nicholls. This information suggests that D.ocoee may actually consist of more than one species. In the Blue Ridge Mountains of northeastern Georgia, a contact zone between two mtDNA haplotypes has been identified. Using starch gel electrophoresis, this study sought to augment the mtDNA data with information from nuclear genes by comparing allele frequencies at six polymorphic allozyme loci among populations of D. ocoee at and around the contact zone. Previous studies have found that allozyme frequencies tend to corroborate mitochondrial sequence data, indicating similar patterns of geographic differentiation among populations. However, the allele frequencies determined by this study do not correlate with the mtDNA data. They show little differentiation between populations in excess of that expected from isolation by distance, suggesting that they belong to the same species