Gene flow and population subdivision in the streamside salamander, Ambystoma barbouri

Gene now is an important determinant of population genetic structure, and u nderstanding patterns of gene flow is especially meaningful in amphibians t o estimate their dispersal capabilities in the face of current wetland dest ruction, In this study, I investigated gene flow using nine polymorphic all ozyme loci in samples from 15 stream sites inhabited by the streamside sala mander, Ambystoma barbouri. Among all 15 sites considered together, gene fl ow was generally low and populations were subdivided genetically. However, on a local level, gene Row was significantly higher between some pairs of s treams and within some neighborhoods (groups of populations within 5 km of each other). Samples from all sites showed sufficient genetic subdivision t o warrant salamander populations from each site to be considered as separat e genetic populations. Sunfish that are major predators of larval streamsid e salamanders appear to act as a barrier to gene flow. This result was supp orted by significant genetic subdivision between two sites sampled within t he same stream and separated by fish pools and two adjacent streams separat ed by areas with high fish densities but a geographic distance of less than a kilometer, As predicted by isolation-by-distance models, gene flow was s ignificantly negatively correlated with geographic distance.