Data from: Glacial refugia, recolonisation patterns, and diversification forces in Alpine-endemic Megabunus harvestmen

The Pleistocene climatic fluctuations had a huge impact on all life-forms, and various hypotheses regarding the survival of organisms during glacial periods have been postulated. In the European Alps, evidence has been found in support of refugia outside the ice shield (massifs de refuge) acting as sources for postglacial recolonisation of inner-Alpine areas. In contrast, evidence for survival on nunataks, ice-free areas above the glacier, remains scarce. Here, we combine multivariate genetic analyses with ecological niche models (ENMs) through multiple timescales to elucidate the history of alpine Megabunus harvestmen throughout the ice ages, a genus that comprises eight high altitude endemics. ENMs suggest two types of refugia throughout the Last Glacial Maximum, inner-Alpine survival on nunataks for four species and peripheral refugia for further four species. In some geographic regions, the patterns of genetic variation are consistent with long-distance dispersal out of massifs de refuge, repeatedly coupled with geographic parthenogenesis. In other regions, long-term persistence in nunataks may dominate the patterns of genetic divergence. Overall, our results suggest that glacial cycles contributed to allopatric diversification in Alpine Megabunus, both within and at the margins of the ice shield. These findings exemplify the power of ENM projections coupled with genetic analyses to identify hypotheses about the position and number of glacial refugia and thus to evaluate the role of Pleistocene glaciations in driving species-specific responses of recolonisation or persistence that may have contributed to observed patterns of biodiversity.更新世（Pleistocene）的气候波动对所有生命类群均产生了深远影响，学界已提出多种关于冰期生物生存策略的假说。在欧洲阿尔卑斯山区，已有研究证据支持冰盖（ice shield）外围存在避难所（massifs de refuge），这些避难所可作为冰期后阿尔卑斯内陆地区种群再定殖的物种源。与之相对，关于物种在冰原岛峰（nunataks，冰川上方的无冰区域）存活的相关证据仍较为匮乏。 本研究结合多变量遗传分析与多时间尺度生态位模型（ENMs），旨在阐明冰期以来阿尔卑斯山区大盲蛛属（Megabunus）——一类包含8种高海拔特有物种的盲蛛类群——的演化历史。生态位模型结果显示，在末次冰盛期（Last Glacial Maximum）存在两类避难所：4个物种通过冰原岛峰在阿尔卑斯内陆存活，另外4个物种则依托外围避难所存续。 在部分地理区域，遗传变异模式与从避难山体（massifs de refuge）进行长距离扩散的结果相符，且该过程多次伴随地理孤雌生殖（geographic parthenogenesis）现象。在其他区域，冰原岛峰上的长期存续可能主导了遗传分化的模式。 综合来看，本研究结果表明，冰期循环推动了阿尔卑斯大盲蛛属在冰盖内部及边缘区域的异域分化（allopatric diversification）。本研究结果亦印证了：将生态位模型投影与遗传分析相结合，可有效验证关于冰期避难所位置与数量的相关假说，进而评估更新世冰期如何驱动物种呈现各异的再定殖或存续策略，而这些策略正是当前生物多样性格局形成的重要驱动因素。