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 dataset 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）对诸多物种种内遗传多样性格局产生了深远影响。鉴于该时期多数温带高山生物的栖息地均被冰川覆盖，其分布范围大概率经历了剧烈变动。尽管冰期的影响已相对明晰，但冰期避难所的空间位置，以及塑造当前遗传多样性格局的演化过程，仍鲜为人知。本研究依托微卫星（microsatellite）数据集，对内华达山脉（Sierra Nevada）的蹼足蝾螈属（Hydromantes，web-toed salamanders）展开种群连通性与避难所隔离假说的验证。我们否决了“避难所经种群扩张后占据南内华达高海拔区域或低海拔欧文斯谷（Owens Valley）”的模型，转而支持一种现存种群间无基因交流的简单隔离模型。通过对南内华达区域开展的多种分析，我们未发现哪怕中等空间尺度下存在基因流动的证据；而北内华达区域仅存在有限的基因交流。上述结果表明，生境破碎化后的隔离分化是塑造该类蝾螈物种遗传变异格局的主导过程。在人为气候变化与生境退化的背景下，本研究结果提示，蝾螈及其他扩散能力较弱的高山生物面临种群衰退风险，因其难以实现长距离迁移。