The evolutionary outcomes of high elevation adaptation have been extensively described. However, whether widely distributed high elevation endemic animals adopt uniform mechanisms during adaptation to different elevational environments remains unknown, especially with respect to extreme high elevation environments. To explore this, we analysed the phenotypic and genomic data of seven populations of plateau zokor (Myospalax baileyi) along elevations ranging from 2,700 to 4,300 m. Based on whole-genome sequencing data and demographic reconstruction of the evolutionary history, we show that two populations of plateau zokor living at elevations exceeding 3,700 m diverged from other populations nearly 10,000 years ago. Further, phenotypic comparisons reveal stress-dependent adaptation, as two populations living at elevations exceeding 3,700 m have elevated ratios of heart mass to body mass relative to other populations, and the highest population (4,300 m) displays alterations in erythrocytes. Correspondingly, genomic analysis of selective sweeps indicates that positive selection might contribute to the observed phenotypic alterations in these two extremely high elevation populations, with the adaptive cardiovascular phenotypes of both populations possibly evolving under the functional constrains of their common ancestral population. Taken together, phenotypic and genomic evidence demonstrates that heterogeneous stressors impact adaptations to extreme elevations and reveals stress-dependent and genetically constrained adaptation to hypoxia, collectively providing new insights into the high elevation adaptation.

中文翻译：

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高原鼢鼠 (Myospalax baileyi) 极高海拔的表型和基因组适应

高海拔适应的进化结果已被广泛描述。然而，广泛分布的高海拔地方性动物在适应不同海拔环境的过程中是否采用统一的机制仍然未知，特别是在极端高海拔环境方面。为了探索这一点，我们分析了七个高原鼢鼠（Myospalax baileyi ）种群的表型和基因组数据。) 沿海拔 2,700 至 4,300 米不等。基于全基因组测序数据和进化史的人口统计学重建，我们表明，生活在海拔超过 3,700 m 的两个高原鼢鼠种群在近 10,000 年前与其他种群分道扬镳。此外，表型比较揭示了压力依赖性适应，因为生活在海拔超过 3,700 m 的两个人群相对于其他人群的心脏质量与体重的比率升高，而最高人群（4,300 m）显示红细胞的变化。相应地，选择性扫描的基因组分析表明，正选择可能有助于在这两个极高海拔种群中观察到的表型改变，两个种群的适应性心血管表型可能在其共同祖先种群的功能约束下进化。总之，表型和基因组证据表明，异质压力源会影响对极端海拔的适应，并揭示对缺氧的压力依赖性和遗传受限的适应，共同为高海拔适应提供新的见解。