Parallel molecular evolution in pathways, genes, and sites in high-elevation hummingbirds revealed by comparative transcriptomics

High-elevation organisms experience shared environmental challenges that include low oxygen availability, cold temperatures, and intense UV radiation. Consequently, repeated evolution of the same genetic mechanisms may occur across high-elevation taxa. To test this prediction, we investigated the extent to which the same biochemical pathways, genes, or sites were subject to parallel molecular evolution for 12 Andean hummingbird species (family: Trochilidae) representing several independent transitions to high elevation across the phylogeny. Across high-elevation species, we discovered parallel evolution for several pathways and genes with evidence of positive selection. In particular, positively selected genes were frequently part of cellular respiration, metabolism, or cell death pathways. To further examine the role of elevation in our analyses, we compared results for low- and high-elevation species and tested different thresholds for defining elevation categories. In analyses with ...

高海拔生物普遍面临着一系列共通的环境胁迫，包括低可利用氧含量、低温以及强紫外线辐射。因此，不同高海拔类群可能会反复演化出相同的遗传机制。为验证这一推测，我们以横跨系统发育树、多次独立向高海拔生境跃迁的12种安第斯蜂鸟（Andean hummingbird，隶属于蜂鸟科（Trochilidae））为研究对象，探究了相同生物化学通路、基因或位点在类群间发生平行分子演化的程度。在高海拔物种中，我们发现多个携带正选择证据的通路与基因发生了平行演化。具体而言，受正选择的基因多富集于细胞呼吸、代谢或细胞死亡通路内。为进一步探究海拔在本研究分析中的作用，我们对比了低海拔与高海拔物种的分析结果，并测试了不同的海拔分类界定阈值。在采用……的分析中