PNAS:对雅库特马的基因组分析

摘要 : 丹麦哥本哈根大学的基因组分析结果阐明了雅库特马的进化起源与遗传适应，这种马在西伯利亚远东寒冷的亚北极地区繁盛生长。

丹麦哥本哈根大学的基因组分析结果阐明了雅库特马的进化起源与遗传适应，这种马在西伯利亚远东寒冷的亚北极地区繁盛生长。有着矮胖的身体、短粗的四肢、华丽的鬃毛以及季节性代谢的雅库特马非常适应吃在寒冷的西伯利亚远东地区常见的被雪覆盖的植被，该地区冬季温度可能降至零下70摄氏度以下。Ludovic Orlando及其同事探索了这种马的遗传起源以及它们的适应的遗传基础。这组作者对9匹现代雅库特马和年代测定为大约5200年前和19世纪早期的2匹古代雄马测定了完整的基因组序列，然后把这些序列与更新世晚期的标本、野生的普氏野马以及驯化品种进行了比较。这项分析提示，雅库特人这个骑马的人群为了肉和奶而饲养这些马，他们很可能在13到15世纪引入了雅库特马的品种，当时他们在这个荒凉的亚北极地形定居下来。这组作者发现了与毛发密度、皮下脂肪储存、身体的表面与质量比以及内分泌响应有关的调控性DNA变化，这些变化很可能让这些马有能力让热损失最小化。与类固醇激素生物合成以及脂肪酸代谢等有关的编码蛋白质的序列的变化，很可能促进了这个品种对冷的耐性。这种马的基因组还拥有在多毛的猛犸以及当地人类身上也独立地进化出来的对寒冷的适应，诸如与毛发和表皮发育、胰岛素代谢以及血管收缩有关的基因的变化，表现出了趋同进化的迹象。这组作者说，除了阐明雅库特马的进化，这些发现还阐明了对极端环境的迅速适应。

原文链接：

Tracking the origins of Yakutian horses and the GENEtic basis for their fast adaptation to subarctic environments

原文摘要：

Yakutia, Sakha Republic, in the Siberian Far East, represents one of the coldest places on Earth, with winter record temperatures dropping below −70 °C. Nevertheless, Yakutian horses survive all year round in the open air due to striking phenotypic adaptations, including compact body conformations, extremely hairy winter coats, and acute seasonal differences in metabolic activities. The evolutionary origins of Yakutian horses and the genetic basis of their adaptations remain, however, contentious. Here, we present the complete genomes of nine present-day Yakutian horses and two ancient specimens dating from the early 19th century and ∼5,200 y ago. By comparing these genomes with the genomes of two Late Pleistocene, 27 domesticated, and three wild Przewalski’s horses, we find that contemporary Yakutian horses do not descend from the native horses that populated the region until the mid-Holocene, but were most likely introduced following the migration of the Yakut people a few centuries ago. Thus, they represent one of the fastest cases of adaptation to the extreme temperatures of the Arctic. We find cis-regulatory mutations to have contributed more than nonsynonymous changes to their adaptation, likely due to the comparatively limited standing variation within gene bodies at the time the population was founded. Genes involved in hair development, body size, and metabolic and hormone signaling pathways represent an essential part of the Yakutian horse adaptive genetic toolkit. Finally, we find evidence for convergent evolution with native human populations and woolly mammoths, suggesting that only a few evolutionary strategies are compatible with survival in extremely cold environments.

doi: 10.1073/PNAS.1513696112

作者：Pablo Librado

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