Data from: Phylogeographic and population genetic analyses reveal Pleistocene isolation followed by high gene flow in a wide- ranging, but endangered, freshwater mussel

Freshwater organisms of North America have had their contemporary genetic structure shaped by vicariant events, especially Pleistocene glaciations. Life history traits promoting dispersal and gene flow continue to shape population genetic structure. Cumberlandia monodonta, a widespread but imperiled (IUCN listed as endangered) freshwater mussel, was examined to determine genetic diversity and population genetic structure range-wide. MtDNA sequences and microsatellite loci were used to measure genetic diversity and simulate demographic events during the Pleistocene using approximate Bayesian computation (ABC) to test explicit hypotheses explaining the evolutionary history of current populations. A phylogeny and molecular clock suggested past isolation created two mtDNA lineages during the Pleistocene that are now widespread. Two distinct groups were also detected with microsatellites. ABC simulations indicated the presence of two glacial refugia and post-glacial admixture of them followed by simultaneous dispersal throughout the current range of the species. The Ouachita population is distinct from others and has the lowest genetic diversity, indicating that this is a peripheral population of the species. Gene flow within this species has maintained high levels of genetic diversity in northern populations, however, all population have experienced fragmentation. Extirpation from the center of its range likely has isolated remaining populations due to the geographic distances among them.北美淡水生物的现代遗传结构深受异域分异事件塑造，其中更新世冰期事件的影响尤为突出。而促进扩散与基因交流的生活史特征，至今仍持续影响着种群的遗传结构。本研究以分布广泛但受威胁的淡水蚌类单齿圆蚌（Cumberlandia monodonta）为研究对象——该物种已被世界自然保护联盟（International Union for Conservation of Nature, IUCN）列为濒危物种，旨在解析其全域分布范围内的遗传多样性与种群遗传结构。研究采用线粒体DNA（MtDNA）序列与微卫星位点对遗传多样性进行评估，并借助近似贝叶斯计算（approximate Bayesian computation, ABC）模拟更新世时期的种群动态事件，以检验解释当前种群演化历史的明确假说。系统发育分析与分子钟校准结果显示，更新世时期的种群隔离曾形成两个线粒体DNA谱系，如今这两个谱系已广泛分布于该物种的整个分布范围。微卫星分析同样检测到两个显著分化的种群类群。近似贝叶斯计算模拟结果表明，该物种曾存在两处冰期避难所，冰期结束后两类群发生遗传混合，并随即同步扩散至当前的整个分布范围。沃希托种群与其他种群显著分化，且其遗传多样性水平最低，表明该种群为该物种的边缘种群。该物种种内的基因交流维持了北部种群的高水平遗传多样性，但目前所有种群均已遭遇种群破碎化。该物种原分布区核心区域的种群灭绝事件，可能因种群间的地理距离拉大，进一步加剧了残存种群的遗传隔离。