Conservation genetics of two imperiled map turtle species: The Pascagoula map turtle and Pearl River map turtle

Abstract The Pascagoula map turtle Graptemys gibbonsi and the Pearl River map turtle G. pearlensis are endemic to their respective river drainages, the Pascagoula River and Pearl River. Both species are considered imperiled, with anthropogenic activities (e.g., impoundments, pollution) differentially impacting these river systems and their respective species. Genetic assessments have already been completed for the sympatric, federally threatened yellow‐blotched sawback G. flavimaculata of the Pascagoula River and ringed sawback G. oculifera of the Pearl River, pursuant to the Endangered Species Act; however, the megacephalic Pascagoula map turtle and Pearl River map turtle occupy different ecological niches and may show different patterns of genetic structure than the microcephalic sawbacks. We used up to 11 microsatellite loci to analyze the population genetic structure and effective population size of the Pascagoula map turtle and Pearl River map turtle sampled throughout their ranges. For the Pascagoula map turtle, the STRUCTURE results indicated two well‐supported groups (Upper Leaf River and Upper Chickasawhay River) and a third moderately supported group (Pascagoula River). However, the Pearl River map turtle lacked strong genetic structure throughout the Pearl River system. Although a single genetic population was recovered for the Pearl River map turtle, it is not entirely panmictic, as there were private alleles at some sites and evidence of isolation by distance. The genetic structure of both species mirrors the findings of the sympatric yellow‐blotched map turtle and ringed map turtle, possibly reflecting the influence of their respective river drainage's hydrological histories or dendritic structure. Our study provides the first genetic assessment for the Pascagoula map turtle and Pearl River map turtle, which can be used to inform potential reintroduction needs in the future and inform management plans to maintain current levels of genetic diversity and connectivity.