School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS, UK.
University College London, Gower Street, London, WC1E 6BT, UK.
Sci Rep. 2017 Mar 21;7(1):259. doi: 10.1038/s41598-017-00132-9.
Gene loss and gain during genome evolution are thought to play important roles in adaptive phenotypic diversification. Among mammals, bats possess the smallest genomes and have evolved the unique abilities of powered flight and laryngeal echolocation. To investigate whether gene family evolution has contributed to the genome downsizing and phenotypic diversification in this group, we performed comparative evolutionary analyses of complete proteome data for eight bat species, including echolocating and non-echolocating forms, together with the proteomes of 12 other laurasiatherian mammals. Our analyses revealed extensive gene loss in the most recent ancestor of bats, and also of carnivores (both >1,000 genes), although this gene contraction did not appear to correlate with the reduction in genome size in bats. Comparisons of highly dynamic families suggested that expansion and contraction affected genes with similar functions (immunity, response to stimulus) in all laurasiatherian lineages. However, the magnitude and direction of these changes varied greatly among groups. In particular, our results showed contraction of the Olfactory Receptor (OR) gene repertoire in the last common ancestor of all bats, as well as that of the echolocating species studied. In contrast, non-echolocating fruit bats showed evidence of expansion in ORs, supporting a "trade-off" between sensory modalities.
基因的丢失和获得被认为在适应表型多样化过程中发挥着重要作用。在哺乳动物中，蝙蝠拥有最小的基因组，并进化出了独特的飞行和喉返声定位能力。为了研究基因家族的进化是否有助于该类群的基因组缩小和表型多样化，我们对 8 种蝙蝠物种（包括回声定位和非回声定位形式）的完整蛋白质组数据进行了比较进化分析，同时还分析了 12 种其他劳亚兽类哺乳动物的蛋白质组数据。我们的分析揭示了蝙蝠和食肉动物（均>1000 个基因）最近共同祖先的广泛基因丢失，尽管这种基因收缩似乎与蝙蝠的基因组大小减少无关。高度动态家族的比较表明，扩张和收缩影响了劳亚兽类所有谱系中具有相似功能（免疫、对刺激的反应）的基因。然而，这些变化的幅度和方向在不同的群体之间差异很大。特别是，我们的结果表明，在所有蝙蝠的最后共同祖先中，嗅觉受体（OR）基因库发生了收缩，所研究的回声定位物种也是如此。相比之下，非回声定位的果蝠显示出 OR 扩张的证据，支持了感觉模式之间的“权衡”。
