Department of Biological Sciences, University of Manitoba, Winnipeg, Canada.
Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China.
Elife. 2021 Apr 29;10:e66797. doi: 10.7554/eLife.66797.
The speciose mammalian order Eulipotyphla (moles, shrews, hedgehogs, solenodons) combines an unusual diversity of semi-aquatic, semi-fossorial, and fossorial forms that arose from terrestrial forbearers. However, our understanding of the ecomorphological pathways leading to these lifestyles has been confounded by a fragmentary fossil record, unresolved phylogenetic relationships, and potential morphological convergence, calling for novel approaches. The net surface charge of the oxygen-storing muscle protein myoglobin (Z), which can be readily determined from its primary structure, provides an objective target to address this question due to mechanistic linkages with myoglobin concentration. Here, we generate a comprehensive 71 species molecular phylogeny that resolves previously intractable intra-family relationships and then ancestrally reconstruct Z evolution to identify ancient lifestyle transitions based on protein sequence alone. Our phylogenetically informed analyses confidently resolve fossorial habits having evolved twice in talpid moles and reveal five independent secondary aquatic transitions in the order housing the world's smallest endothermic divers.
多齿鼩形目（鼹鼠、鼩鼱、刺猬、鳞尾鼯鼠）是一个种类繁多的哺乳动物目，包括许多半水生、半穴居和穴居的物种，它们起源于陆生祖先。然而，由于化石记录不完整、系统发育关系尚未解决以及潜在的形态趋同，我们对导致这些生活方式的生态形态途径的理解一直受到阻碍，这需要新的方法。储氧肌肉蛋白肌红蛋白 (Z) 的净表面电荷可以通过其一级结构来确定，由于与肌红蛋白浓度的机械联系，这为解决这个问题提供了一个客观的目标。在这里，我们生成了一个全面的 71 种分子系统发育关系，解决了以前难以解决的家族内关系，然后从蛋白质序列上重建 Z 的进化，以确定基于蛋白序列的古老生活方式的转变。我们的系统发育信息分析明确解决了在鼩鼱科中进化了两次的穴居习性，并揭示了在这个目中有五个独立的次生水生转变，其中包括世界上最小的恒温潜水动物。
