Quaternary climate fluctuations are an engine of biotic diversification. Global cooling cycles, such as the Last Glacial Maximum (LGM), are known to have fragmented the ranges of higher-latitude fauna and flora into smaller refugia, dramatically reducing species ranges. However, relatively less is known about the effects of cooling cycles on tropical biota. We analyzed thousands of genome-wide DNA markers across an assemblage of three closely related understorey-inhabiting scrubwrens (Sericornis and Aethomyias; Aves) from montane forest along an elevational gradient on Mt. Wilhelm, the highest mountain of Papua New Guinea. Despite species-specific differences in elevational preference, we found limited differentiation within each scrubwren species, but detected a strong genomic signature of simultaneous population expansions at 27-29 ka, coinciding with the onset of the LGM. The remarkable synchronous timing of population expansions of all three species demonstrates the importance of global cooling cycles in expanding highland habitat. Global cooling cycles have likely had strongly different impacts on tropical montane areas versus boreal and temperate latitudes, leading to population expansions in the former and serious fragmentation in the latter.

中文翻译：

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末次盛冰期导致巴布亚新几内亚高原山地鸣禽辐射范围内的种群数量扩张。


第四纪气候波动是生物多样化的引擎。众所周知，全球变冷周期，例如末次盛冰期（LGM），已将高纬度动植物群的范围分割成较小的避难所，从而大大减少了物种范围。然而，人们对冷却循环对热带生物群的影响知之甚少。我们分析了巴布亚新几内亚最高峰威廉山沿海拔梯度山地森林中三种密切相关的林下灌木鹩莺（Sericornis 和 Aethomyias；Aves）的组合中的数千个全基因组 DNA 标记。尽管不同物种在海拔偏好方面存在差异，但我们发现每个灌木鹩莺物种内部的分化有限，但在 27-29ka 时检测到了种群同时扩张的强烈基因组特征，这与末次盛宴的开始时间一致。所有三个物种的种群扩张的显着同步时间表明了全球冷却循环对于扩大高地栖息地的重要性。全球变冷循环可能对热带山地地区与北半球和温带纬度地区产生截然不同的影响，导致前者人口扩张，而后者人口严重分裂。