Geographic Protein Variation and Divergence in the Salamanders of the Plethodon Welleri Group (Amphibia, Plethodontidae)

Variation in 26 loci coding for the production of protein products is analyzed in three populations of Plethodon welleri and in 26 populations of Plethodon dorsalis. Protein variation patterns are not consistent with the variation of morphological characters upon which the taxonomic status of these populations has been evaluated. The taxonomic division of P. welleri into subspecies is inconsistent with the electrophoretic data. P. dorsalis includes two groups of populations whose electrophoretic divergence is greater than that observed in any species previously studied. They do not correspond with previously recognized subspecies. Measures of genetic identity (Nei’s I) and of population subdivision (Wright’s FST) indicate that P. dorsalis is divided into a number of genetically isolated units. The FST values reported for this species are greater than any such values reported previously. It is suggested that the taxonomic recognition of species denotes the presence of a highly canalized phenotype which has been maintained over genetically diverse populations, rather than the genetically homogeneous units of other vertebrate species. Morphological divergence appears to be unrelated to the amount of electrophoretically detected genetic differentiation occurring among populations of the P. welleri group.