Data from: Hot spots of genetic diversity descended from multiple Pleistocene refugia in an alpine ungulate

Species that inhabit naturally fragmented environments are expected to be spatially structured and exhibit reduced genetic diversity at the periphery of their range. Patterns of differentiation may also reflect historical processes such as recolonization from glacial refugia. We examined the relative importance of these factors in shaping the spatial patterns of genetic differentiation across the range of an alpine specialist, the North American mountain goat (Oreamnos americanus). Contrary to fossil evidence which suggests a single southern refugium, we detected evidence for additional refugia in northern British Columbia and the Alaskan coast using both mitochondrial and microsatellite DNA. A core area of elevated genetic diversity characterized both regions, and molecular dating suggested a recent Pleistocene split was followed by demographic expansion. Across their range, mountain goats were highly genetically structured and displayed the expected pattern of declining diversity towards the periphery. Gene flow was high within contiguous mountain ranges, but cross-assignments paradoxically suggest that long-distance contemporary dispersal movements are not uncommon. These results improve our understanding of how historical vicariance and contemporary fragmentation influence population differentiation, and have implications for conserving the adaptive potential of alpine populations and habitat.

栖息于自然生境破碎化环境中的物种，通常会呈现空间遗传结构特征，且在其分布范围边缘地带的遗传多样性会出现降低现象。遗传分化模式同样可能反映诸如冰期避难所再定植等历史演化过程。本研究以高山特化物种——北美雪羊（Oreamnos americanus）为研究对象，探究上述两类因素对其整个分布范围内遗传分化空间格局的相对影响强度。与认为仅存在南部单一冰期避难所的化石证据相悖，本研究通过线粒体DNA（mitochondrial DNA）和微卫星DNA（microsatellite DNA）两种分子标记，在不列颠哥伦比亚省北部及阿拉斯加沿岸发现了额外的冰期避难所证据。这两个区域均存在遗传多样性升高的核心区域，分子定年结果显示，其在更新世（Pleistocene）发生了近期的种群分化事件，随后经历了种群扩张过程。在整个分布范围内，北美雪羊呈现出高度的遗传结构特征，且表现出预期的"向分布边缘遗传多样性逐渐降低"的模式。在连续的山地生境中，种群间的基因流水平较高，但种群归属交叉分析的结果却反常地显示，当代的长距离扩散事件并不罕见。本研究结果加深了我们对历史隔离事件与当代生境破碎化如何影响种群分化的理解，同时对高山种群及其生境的适应性潜能保护工作具有重要参考价值。