Data from: Evolutionary reconstruction supports the presence of a Pleistocene Arctic refugium for a large mammal species

Aim: The presence of refugia in the Canadian High Arctic has been subject to debate for decades. We investigated the potential existence of Arctic refugia during the Pleistocene for a large mammal species in the Canadian Archipelago because if these refugia were present, reconsideration of the evolutionary histories of North American fauna and flora beyond the major refugia of Beringia and south of the Laurentide and Cordilleran Ice Sheets would be required. Peary caribou (Rangifer tarandus pearyi), identified as a subspecies based on morphological characteristics, inhabits the Canadian Arctic Islands and Boothia Peninsula. Previous studies demonstrated incomplete lineage sorting of mitochondrial DNA interpreted as a Beringian origin but were based on small sample sizes. Location: Canadian Arctic. Major taxa studied: Mammals: caribou (Rangifer tarandus). Methods: We used two molecular markers (microsatellites and mitochondrial DNA) and approximate Bayesian computations (ABC) testing the hypotheses of colonization out of Beringia into the Arctic Islands following the Last Glacial Maximum (LGM) or a divergence from Beringia significantly before the end of the LGM within a different refugium. Results: The coalescent-based analyses rejected a recent Beringian origin with subsequent colonization, instead supporting a divergence of Peary caribou from Beringia ~100,000 years ago linking it to the last interglacial/early Wisconsin Glacial Stage (125,000–75,000 years ago). Admixture on Banks Island with Beringian-derived barren-ground caribou is indicative of post-Pleistocene secondary contact; further supporting a divergent history of Peary caribou within a separated Arctic refugium. Main conclusions: Our results offer support for the existence of an Arctic refugium for large mammal species and add to the increasing evidence of such refugia in North America. This has significant implications on understanding the evolution and conservation of Arctic species, particularly in light of sensitivities and adaptive potential to a rapidly changing climate.研究目的：加拿大高北极地区是否存在冰期避难所（refugia）这一议题已争论数十年。本研究针对加拿大群岛内的大型哺乳动物类群，探究更新世（Pleistocene）北极冰期避难所的潜在存在性——若此类避难所确实存在，则需重新审视白令陆桥（Beringia）以外、劳伦泰德与科迪勒拉冰盖以南区域的北美动植物演化历史。皮尔里驯鹿（*Rangifer tarandus pearyi*）是基于形态特征划定的亚种，栖息于加拿大北极群岛与布西亚半岛。既往研究因样本量较小，将其线粒体DNA的不完全谱系分选现象解读为白令陆桥起源，但该结论尚存局限。 研究区域：加拿大北极地区。 研究类群：哺乳动物——驯鹿（*Rangifer tarandus*）。 研究方法：本研究采用微卫星（microsatellites）与线粒体DNA两种分子标记，并借助近似贝叶斯计算（ABC）检验两类假说：其一为末次盛冰期（LGM）后从白令陆桥向北极群岛扩散定植；其二为早于末次盛冰期结束前，该类群于另一独立避难所中与白令陆桥种群发生分化。 研究结果：基于溯祖分析的结果拒绝了“近期从白令陆桥起源并后续扩散定植”的假说，转而支持皮尔里驯鹿约于10万年前与白令陆桥种群发生分化，该分化事件与末次间冰期/威斯康星冰期早期（12.5万至7.5万年前）相吻合。班克斯岛存在皮尔里驯鹿与白令陆桥起源的瘠地驯鹿的基因交流现象，表明更新世后存在二次接触，进一步佐证了皮尔里驯鹿于独立北极避难所中发生分化的演化历史。 主要结论：本研究结果为大型哺乳动物存在北极冰期避难所提供了实证支撑，进一步丰富了北美地区此类冰期避难所的相关研究证据。该发现对于理解北极物种的演化与保护具有重要意义，尤其在当前气候快速变化的背景下，物种对环境变化的敏感性与适应潜力值得重点关注。