Evolution and phylogenetic application of the MC1R gene in the Cobitoidea (Teleostei: Cypriniformes)
Evolution and phylogenetic application of the MC1R gene in the Cobitoidea (Teleostei: Cypriniformes)
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MC1R 基因在鳅总科 (Teleostei: Cypriniformes) 中的进化和系统发育应用
DOI：
10.13918/j.issn.2095-8137.2016.5.281
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发表时间：
2016-09-18
影响因子：
4.9
通讯作者：
Liu, Huan-Zhang
中科院分区：
文献类型：
--
作者：
Tang, Qiong-Ying;Shi, Li-Xia;Liu, Huan-Zhang
泥鳅总科的鱼类具有极高的颜色模式多样性，但迄今为止对其进化机制知之甚少。黑皮质素1受体基因（MC 1 R）在黑色素的合成和动物体色图案的形成过程中发挥着重要作用。本研究对来自4个科31个种的44个泥鳅个体的MC 1 R基因部分序列进行了扩增和测序。系统发育分析得到的拓扑结构与以前的研究一致，使用多个核基因座，表明每个家庭是单系与姐妹关系的Botiidae+（鳅科+（Balitoridae+Nemacheilidae））。基因进化分析表明，泥鳅MC 1 R处于纯化选择压力下，不同位点的dN/ds值不同。Botiidae和Cobitidae的dN/ds值都低于背景谱系，表明它们的进化可能受到纯化选择压力的强烈影响。Balitoridae和Nemachelidae的dN/ds值均大于背景谱系，表明它们在更宽松的选择压力下具有更快的进化速率。因此，我们推测，相对稳定的颜色模式Botiidae和Cobitidae可能是由于强大的纯化选择压力的MC 1 R基因，而复杂多样的颜色模式Balitoridae和Nemachelidae可能与宽松的选择压力。鉴于MC 1 R基因部分片段的实验操作简单，在重建系统发育方面表现优异，我们认为该基因可作为鱼类系统发育研究的良好分子标记。
Fish of the superfamily Cobitoidea sensu stricto (namely loaches) exhibit extremely high diversity of color patterns, but so far little is known about their evolutionary mechanism. Melanocortin 1 receptor gene (MC1R) plays an important role during the synthesis of melanin and formation of animal body color patterns. In this study, we amplified and sequenced the partial MC1R gene for 44 loach individuals representing 31 species of four families. Phylogenetic analyses yielded a topology congruent with previous studies using multiple nuclear loci, showing that each of the four families was monophyletic with sister relationships of Botiidae+ (Cobitidae+(Balitoridae+Nemacheilidae)). Gene evolutionary analyses indicated that MC1R in loaches was under purifying selection pressure, with various sites having different dN/ds values. Both Botiidae and Cobitidae had lower dN/ds values than those of background lineages, suggesting their evolution might be strongly affected by purifying selection pressure. For Balitoridae and Nemacheilidae, both had larger dN/ds values than those of background lineages, suggesting they had a faster evolutionary rate under more relaxed selection pressure. Consequently, we inferred that the relatively stable color patterns in Botiidae and Cobitidae might result from the strong purifying selection pressure on the MC1R gene, whereas the complicated and diverse color patterns in Balitoridae and Nemacheilidae might be associated with the relaxed selection pressure. Given the easy experimental procedure for the partial MC1R gene and its excellent performance in reconstructing phylogeny, we suggest this gene could be used as a good molecular marker for the phylogenetic study of fish species.