Understanding spatial patterns of biodiversity within the context of long-term climatic shifts is of high importance, particularly in the face of contemporary climate change. In comparison to aboveground taxa, subterranean organisms respond to changing climates with generally much lower dispersal and recolonization potential, yet possible persistence in refugial groundwater habitats under ice-shields. However, knowledge on general and geographically large-scale effects of glaciation on contemporary groundwater biodiversity patterns is still very limited. Here, we tested how Late Pleistocene glaciation influenced the diversity and distribution of 36 groundwater amphipod species in Alpine and peri-Alpine regions, characterized by extensive glaciation cycles, and how its legacy explains contemporary diversity patterns. We based our analysis on an unprecedented density of ~ 1000 systematic sampling sites across Switzerland. Using presence–absence data, we assessed biodiversity and species' ranges, and calculated for each site within-catchment distance to the Last Glacial Maximum (LGM) glacier extent. We then applied a sliding window approach along the obtained distance gradient from LGM ice-covered to ice-free sites to compute biodiversity indices reflecting local richness, regional richness, and differentiation, respectively. We found a strong signal of the LGM ice extent on the present-day distribution of groundwater amphipods. Our findings revealed pronounced species turnover and spatial envelopes of individual species' occurrences in formerly ice-covered, ice-free, or transitional zones, respectively. While local richness remained constant and low along the LGM distance gradient, groundwater communities in LGM ice-covered areas were more similar to each other and had lower gamma diversities and decreased occurrence probabilities per sliding window compared to communities in Pleistocene ice-free areas. These results highlight the significant impact of Pleistocene glaciation on shaping biodiversity patterns of subterranean communities and imprinting contemporary distribution of groundwater organisms.

中文翻译：

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晚更新世冰川梯度沿线地下生物多样性模式的显着变化


了解长期气候变化背景下生物多样性的空间格局非常重要，特别是面对当代气候变化。与地上类群相比，地下生物对气候变化的反应通常具有较低的扩散和再殖民潜力，但可能在冰盖下的避难地下水栖息地中持续存在。然而，关于冰川作用对当代地下水生物多样性模式的一般和地理大范围影响的知识仍然非常有限。在这里，我们测试了晚更新世冰川作用如何影响高山和近阿尔卑​​斯地区以广泛的冰川周期为特征的 36 种地下水片脚类物种的多样性和分布，以及其遗产如何解释当代多样性模式。我们的分析基于瑞士各地约 1000 个系统采样点的空前密度。使用存在-不存在数据，我们评估了生物多样性和物种范围，并计算了流域内到末次盛冰期（LGM）冰川范围的距离内的每个地点。然后，我们沿着所获得的从末次海冰覆盖到无冰地点的距离梯度应用滑动窗口方法来计算分别反映局部丰富度、区域丰富度和差异的生物多样性指数。我们在现今地下水片足类动物的分布上发现了末次盛冰期冰范围的强烈信号。我们的研究结果揭示了明显的物种更替和单个物种出现的空间范围，分别位于以前的冰覆盖、无冰或过渡带。 虽然沿末次盛冰期距离梯度局部丰富度保持恒定且较低，但与更新世无冰地区的群落相比，末次盛冰期冰覆盖地区的地下水群落彼此更加相似，伽马多样性较低，每个滑动窗口的出现概率也较低。这些结果强调了更新世冰川作用对塑造地下群落生物多样性模式和影响地下水生物当代分布的重大影响。