Division of Biology, Kansas State University, Manhattan, Kansas, USA.
Alaska Department of Fish and Game, Anchorage, Alaska, USA.
Mol Ecol. 2022 Oct;31(20):5231-5248. doi: 10.1111/mec.16658. Epub 2022 Aug 26.
Episodes of Quaternary environmental change shaped the genomes of extant species, influencing their response to contemporary environments, which are changing rapidly. Island endemics are among the most vulnerable to such change, accounting for a disproportionate number of recent extinctions. To prevent extinctions and conserve island biodiversity it is vital to combine knowledge of species' ecologies with their complex evolutionary histories. The Bering Sea has a history of cyclical island isolation and reconnection, coupled with modern rates of climate change that exceed global averages. The endangered Pribilof Island shrew (Sorex pribilofensis) is endemic to St. Paul Island, Alaska, which was isolated from mainland Beringia ~14,000 years ago by rising sea levels. Using ~11,000 single nucleotide polymorphisms, 17 microsatellites and mitochondrial sequence data, we test predictions about the evolutionary processes driving shrew speciation across Beringia. Our data show considerable differentiation of S. pribilofensis from mainland sibling species, relative to levels of divergence between mainland shrews. We also find a genome-wide loss of diversity and extremely low N for S. pribilofensis. We then show that intraspecific genetic diversity is significantly related to interspecific divergence, and that differentiation between S. pribilofensis and other Beringian shrews is highest across loci that are fixed in S. pribilofensis, indicating that strong drift has driven differentiation of this island species. Our findings show that drift as a consequence of Arctic climate cycling can rapidly reshape insular biodiversity. Arctic island species that lack genomic diversity and have evolved in response to past climate may have limited ability to respond to modern environmental changes.
第四纪环境变化塑造了现存物种的基因组，影响了它们对快速变化的当代环境的反应。岛屿特有种是最容易受到这种变化影响的物种之一，它们在最近的灭绝事件中占了不成比例的数量。为了防止灭绝和保护岛屿生物多样性，将物种的生态知识与其复杂的进化历史相结合至关重要。白令海经历了周期性的岛屿隔离和重新连接，加上现代气候变化的速度超过了全球平均水平。濒危的普里比洛夫岛鼩鼱（Sorex pribilofensis）是阿拉斯加圣保罗岛的特有种，大约 14000 年前，由于海平面上升，它与白令大陆隔离。利用大约 11000 个单核苷酸多态性、17 个微卫星和线粒体序列数据，我们检验了关于驱动白令地区鼩鼱物种形成的进化过程的预测。我们的数据显示，与大陆鼩鼱之间的分化水平相比，S. pribilofensis 与大陆亲缘物种之间存在相当大的分化。我们还发现 S. pribilofensis 的基因组多样性丧失和极低的 N 值。然后，我们表明种内遗传多样性与种间分化显著相关，并且 S. pribilofensis 与其他白令地区鼩鼱之间的分化在固定于 S. pribilofensis 的位点上最高，这表明强烈的漂变驱动了这个岛屿物种的分化。我们的研究结果表明，由于北极气候循环引起的漂变可以迅速重塑岛屿生物多样性。缺乏基因组多样性且已进化以适应过去气候的北极岛屿物种可能对现代环境变化的适应能力有限。
