Ice-Age Climate Adaptations Trap the Alpine Marmot in a State of Low Genetic Diversity
Ice-Age Climate Adaptations Trap the Alpine Marmot in a State of Low Genetic Diversity
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DOI：
10.1016/j.cub.2019.04.020
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发表时间：
2019-05-20
期刊：
影响因子：
9.2
通讯作者：
Ralser, Markus
中科院分区：
文献类型：
--
作者：
Gossmann, Toni I.;Shanmugasundram, Achchuthan;Ralser, Markus
一些物种成功地应对了史前的气候变化[1,2]，而另一些物种则未能适应并灭绝了[1,2]。决定成功适应气候变化的因素仍然知之甚少。我们构建了一个参考基因组，研究了高山旱獭（Marmota Marmota）的生理适应性。旱獭是一种大型地栖松鼠，能很好地适应更新世草原的“冰河时期”气候[4,5]。由于这种栖息地的消失，啮齿动物在高海拔的高寒草甸中仍然大量存在[6,7]。基因组和代谢组显示适应与寒冷气候一致的证据，影响白色脂肪组织。然而，相反地，我们发现高山土拨鼠的遗传变异水平是哺乳动物中最低的，这样有害的突变就不太容易被清除。我们的数据排除了对低多样性的典型解释，比如近亲交配的高水平，或者最近的瓶颈。相反，古代人口重建显示，遗传多样性在更新世的气候变化中消失了，尽管目前的人口规模很大，但尚未恢复。我们将这种缓慢的恢复归因于土拨鼠的适应性生活史。高山旱獭的案例揭示了气候变化、遗传多样性和保护状况之间的复杂关系。它表明，遗传多样性极低的物种可以非常成功并持续数千年，但也表明，适应气候的生活史可以使一个物种长期处于低遗传多样性的状态。
Some species responded successfully to prehistoric changes in climate [1,2], while others failed to adapt and became extinct [3]. The factors that determine successful climate adaptation remain poorly understood. We constructed a reference genome and studied physiological adaptations in the Alpine marmot (Marmota marmota), a large ground-dwelling squirrel exquisitely adapted to the "ice-age" climate of the Pleistocene steppe [4,5]. Since the disappearance of this habitat, the rodent persists in large numbers in the high-altitude Alpine meadow [6,7]. Genome and metabolome showed evidence of adaptation consistent with cold climate, affecting white adipose tissue. Conversely, however, we found that the Alpine marmot has levels of genetic variation that are among the lowest for mammals, such that deleterious mutations are less effectively purged. Our data rule out typical explanations for low diversity, such as high levels of consanguineous mating, or a very recent bottleneck. Instead, ancient demographic reconstruction revealed that genetic diversity was lost during the climate shifts of the Pleistocene and has not recovered, despite the current high population size. We attribute this slow recovery to the marmot's adaptive life history. The case of the Alpine marmot reveals a complicated relationship between climatic changes, genetic diversity, and conservation status. It shows that species of extremely low genetic diversity can be very successful and persist over thousands of years, but also that climate-adapted life history can trap a species in a persistent state of low genetic diversity.