Population dynamics and demographic history of Eurasian collared lemmings. undefined

Background: Ancient DNA studies suggest that Late Pleistocene climatic changes had a significant effect on population dynamics in Arctic species. The Eurasian collared lemming (Dicrostonyx torquatus) is a keystone species in the Arctic ecosystem. Earlier studies have indicated that past climatic fluctuations were important drivers of past population dynamics in this species. Results: Here, we analysed 59 ancient and 54 modern mitogenomes from across Eurasia, along with one modern nuclear genome. Our results suggest population growth and genetic diversification during the early Late Pleistocene, implying that collared lemmings may have experienced a genetic bottleneck during the warm Eemian interglacial. Furthermore, we find multiple temporally structured mitogenome clades during the Late Pleistocene, consistent with earlier results suggesting a dynamic late glacial population history. Finally, we identify a population in northeastern Siberia that maintained genetic diversity and a constant population size at the end of the Pleistocene, suggesting suitable conditions for collared lemmings in this region during the increasing temperatures associated with the onset of the Holocene. Conclusions: This study highlights an influence of past warming, in particular the Eemian interglacial, on the evolutionary history of the collared lemming, along with spatiotemporal population structuring throughout the Late Pleistocene.

研究背景：古DNA（Ancient DNA）研究表明，晚更新世（Late Pleistocene）气候变迁对北极物种的种群动态具有显著影响。欧亚领旅鼠（Eurasian collared lemming，*Dicrostonyx torquatus*）是北极生态系统中的关键物种（keystone species）。此前已有研究指出，过往的气候波动是该物种种群动态变化的重要驱动因素。研究结果：本研究对欧亚大陆范围内的59个古DNA样本与54个现代样本的线粒体基因组（mitogenomes）进行了分析，同时纳入1个现代核基因组（nuclear genome）。结果显示，晚更新世早期该物种曾经历种群扩张与遗传多样化，暗示领旅鼠可能在温暖的埃姆间冰期（Eemian interglacial）遭遇过遗传瓶颈（genetic bottleneck）。此外，我们在晚更新世地层中发现了多个具有时间结构特征的线粒体基因组演化支（clades），这与此前研究提出的晚冰期种群动态复杂多变的结论相符。最后，我们在西伯利亚东北部鉴定出一个种群，其在更新世末期仍维持着遗传多样性与稳定的种群规模，表明在全新世（Holocene）起始阶段的气温上升时期，该区域仍具备适合领旅鼠生存的环境条件。研究结论：本研究揭示了过往气候变暖（尤其是埃姆间冰期）对领旅鼠演化历史的影响，同时阐明了晚更新世期间该物种种群的时空结构特征。