Dussex Nicolas, Tørresen Ole K, van der Valk Tom, Le Moullec Mathilde, Veiberg Vebjørn, Tooming-Klunderud Ave, Skage Morten, Garmann-Aarhus Benedicte, Wood Jonathan, Rasmussen Jacob A, Pedersen Åshild Ø, Martin Sarah L F, Røed Knut H, Jakobsen Kjetill S, Dalén Love, Hansen Brage B, Martin Michael D
Department of Natural History, University Museum, Norwegian University of Science and Technology (NTNU), Erling Skakkes gate 47A, Trondheim, Norway.
Centre for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, PO Box 1066 Blindern, N-0316 Oslo, Norway.
iScience. 2023 Sep 3;26(10):107811. doi: 10.1016/j.isci.2023.107811. eCollection 2023 Oct 20.
Typically much smaller in number than their mainland counterparts, island populations are ideal systems to investigate genetic threats to small populations. The Svalbard reindeer () is an endemic subspecies that colonized the Svalbard archipelago ca. 6,000-8,000 years ago and now shows numerous physiological and morphological adaptations to its arctic habitat. Here, we report a - chromosome-level assembly for Svalbard reindeer and analyze 133 reindeer genomes spanning Svalbard and most of the species' Holarctic range, to examine the genomic consequences of long-term isolation and small population size in this insular subspecies. Empirical data, demographic reconstructions, and forward simulations show that long-term isolation and high inbreeding levels may have facilitated the reduction of highly deleterious-and to a lesser extent, moderately deleterious-variation. Our study indicates that long-term reduced genetic diversity did not preclude local adaptation to the High Arctic, suggesting that even severely bottlenecked populations can retain evolutionary potential.
岛屿种群的数量通常比其大陆同类种群少得多，是研究小种群遗传威胁的理想系统。斯瓦尔巴驯鹿（）是一种特有亚种，约在6000 - 8000年前定居于斯瓦尔巴群岛，现在表现出许多对其北极栖息地的生理和形态适应。在这里，我们报告了斯瓦尔巴驯鹿的染色体水平组装，并分析了133个驯鹿基因组，这些基因组涵盖了斯瓦尔巴群岛以及该物种大部分全北区范围，以研究这个岛屿亚种长期隔离和小种群规模的基因组后果。实证数据、种群统计学重建和正向模拟表明，长期隔离和高近亲繁殖水平可能促进了高度有害变异（以及在较小程度上的中度有害变异）的减少。我们的研究表明，长期遗传多样性降低并未妨碍对高北极地区的局部适应，这表明即使是严重瓶颈化的种群也能保留进化潜力。
