Since the advent of molecular tools, hybridization has increasingly been recognized as both a common and an evolutionarily important process. Using single nucleotide polymorphism markers from three nuclear genes, we investigated the extent of hybridization between two terrestrial salamanders (Plethodon cinereus and P. electromorphus) at 13 sites in northeastern Ohio, U.S.A. These markers indicated a high degree of gene flow and introgression in these two species (48 of 90 individuals genotyped were classified as hybrids using a Bayesian assignment algorithm). These hybrids included F1 individuals and backcrosses to both species. These data as well as mitochondrial DNA sequences from hybrids suggest symmetrical hybridization. A multivariate analysis of standard morphological characters and coloration patterns from image analysis demonstrated that hybrids are intermediate in many ways. However, backcrosses proved difficult to separate from parentals, and the extent of hybridization would have been underestimated using morphology and coloration alone. Given the high frequency of hybrids and their broad geographic distribution, we speculate that these two lineages may be in the process of merging back into a single gene pool.

You do not currently have access to this content.