Zou Zhengting, Zhang Jianzhi
Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor.
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor
Mol Biol Evol. 2015 May;32(5):1237-41. doi: 10.1093/molbev/msv014. Epub 2015 Jan 27.
Toothed whales and two groups of bats independently acquired echolocation, the ability to locate and identify objects by reflected sound. Echolocation requires physiologically complex and coordinated vocal, auditory, and neural functions, but the molecular basis of the capacity for echolocation is not well understood. A recent study suggested that convergent amino acid substitutions widespread in the proteins of echolocators underlay the convergent origins of mammalian echolocation. Here, we show that genomic signatures of molecular convergence between echolocating lineages are generally no stronger than those between echolocating and comparable nonecholocating lineages. The same is true for the group of 29 hearing-related proteins claimed to be enriched with molecular convergence. Reexamining the previous selection test reveals several flaws and invalidates the asserted evidence for adaptive convergence. Together, these findings indicate that the reported genomic signatures of convergence largely reflect the background level of sequence convergence unrelated to the origins of echolocation.
齿鲸和两类蝙蝠独立获得了回声定位能力，即通过反射声音来定位和识别物体的能力。回声定位需要生理上复杂且协调的发声、听觉和神经功能，但回声定位能力的分子基础尚未得到充分理解。最近的一项研究表明，回声定位动物蛋白质中广泛存在的趋同氨基酸替换是哺乳动物回声定位趋同起源的基础。在这里，我们表明，回声定位谱系之间分子趋同的基因组特征通常并不比回声定位谱系与可比的非回声定位谱系之间的特征更强。声称富含分子趋同的29种听力相关蛋白质组也是如此。重新审视先前的选择测试发现了几个缺陷，并使所声称的适应性趋同证据无效。总之，这些发现表明，所报道的趋同基因组特征在很大程度上反映了与回声定位起源无关的序列趋同背景水平。
