Data from: Testing models of refugial isolation, colonization and population connectivity in two species of montane salamanders

Pleistocene glaciations have profoundly affected patterns of genetic diversity within many species. Temperate alpine organisms likely experienced dramatic range shifts, given that much of their habitat was glaciated during this time. While the effects of glaciations are relatively well understood, the spatial locations of refugia and processes that gave rise to current patterns of diversity are less well known. We use a microsatellite data set to test hypotheses of population connectivity and refugial isolation in the web-toed salamanders (Hydromantes) of the Sierra Nevada. We reject models of refugia with subsequent expansion into either the high southern Sierra or low-elevation Owens Valley, in favor of a simple isolation model with no migration between current populations. We find no evidence of migration at even moderate spatial scales using a variety of analyses in the southern Sierra, and limited migration in the northern Sierra. These results suggest that divergence in isolation following fragmentation is the dominant process structuring genetic variation in these salamander species. In the context of anthropogenic climate change and habitat degradation, these results imply that salamanders and other low-vagility alpine organisms are at risk of decline as they are unlikely to migrate across large distances.更新世冰期（Pleistocene glaciations）对众多物种种内遗传多样性格局产生了深远影响。温带高山生物的栖息地在此期间大多被冰川覆盖，因此其分布范围大概率经历了剧烈变迁。尽管冰期的影响已得到相对充分的阐释，但避难所（refugia）的空间位置以及塑造当前遗传多样性格局的演化过程，仍未得到足够清晰的认知。本研究利用微卫星数据集（microsatellite data set），对内华达山脉的蹼足蝾螈属（Hydromantes）展开种群连通性与避难所隔离假说的检验。研究结果拒绝了"避难所种群随后向南内华达高海拔区域或低海拔欧文斯谷扩张"的相关模型，转而支持无现存种群间基因交流的简单隔离模型。通过在内华达南部开展的多类分析，即便在中等空间尺度下也未检测到基因交流的迹象；而在内华达北部，仅存在有限的基因流动。上述结果表明，生境破碎化后的隔离分化是塑造这类蝾螈遗传变异格局的主导过程。在当前人为气候变化与生境退化的背景下，本研究结果预示，蝾螈及其他扩散能力较弱的高山生物将面临种群衰退风险，因其难以进行长距离扩散。