Initial Investigation of Population and Conservation Genetics in the Coastal Giant Salamander,Dicamptodon tenebrosus, Using Nuclear Microsatellite Markers

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Population genetics can facilitate efforts to curb amphibian decline by enabling accurate delineation of population boundaries and by characterizing extant genetic diversity. We used data from five microsatellite markers, which are highly variable and thus can resolve fine-scale genetic patterns, to conduct a preliminary investigation of nuclear genetic diversity among broadly distributed populations of coastal giant salamanders (Dicamptodon tenebrosus), a Pacific Northwest endemic threatened by deforestation and habitat fragmentation in the northern part of its range. The main aim was to compare a limited nuclear genetic data set with already available mitochondrial DNA (mtDNA) data and to summarize what available genetic data suggests in terms of conservation management for this species. Multiple measures presented here support that northern and southern groups of coastal giant salamanders are highly divergent genetically. Results presented here were consistent with those from an mtDNA study, thus supporting earlier evidence of very high levels of genetic divergence between northern and southern groupings separated by the Columbia River Valley. Available genetic evidence suggests that conservation management for this species should at minimum recognize these two groups as distinct units. Despite sparse sampling of the southern group of coastal giant salamanders in this study, results showed evidence of remarkably high genetic diversity there such that further study is recommended to fully characterize fine-scale population level structuring, which would ensure that all distinct genetic units within the species have been elucidated.