中国沙塘鳢属鱼类线粒体12S rRNA基因序列分析

沙塘鳢属鱼类为东亚特有的小型淡水经济鱼类,中国产沙塘鳢属鱼类分类问题长期存在争议。本文测定了中国产沙塘鳢属鱼类全部种类的线粒体12S rRNA基因部分序列,结合GenBank中下载的2种日本沙塘鳢属鱼类和塘鳢科鱼类同源序列,探讨中国产4种沙塘鳢属鱼类的物种有效性,分析沙塘鳢属鱼类的系统发育关系。作者所使用的同源序列长度为690bp,其中变异位点258个,简约信息位点201个,包括插入/缺失位点34个,转换/颠换平均值为3.0,表明12S rRNA基因是研究沙塘鳢属鱼类系统发育关系的合适分子标记。基于p-distance模型的6种沙塘鳢属鱼类种内遗传距离为0.000—0.024,种间遗传距离为0.058—0.064,支持暗色沙塘鳢和中华沙塘鳢为不同种,中国产沙塘鳢属鱼类包括中华沙塘鳢、河川沙塘鳢、海丰沙塘鳢、鸭绿江沙塘鳢4个种的观点;至于中国还有没有新的沙塘鳢属鱼类,尚有待进一步研究。系统发育分析表明海丰海塘鳢是河川沙塘鳢的姐妹群,暗色沙塘鳢与O.hikimius的亲缘关系最为密切,而同属其余类群之间的系统发育关系则由于自展数据支持率较低而尚不明确。中国产沙塘鳢和日本产沙塘鳢并未单独分群,推测沙塘鳢属鱼类的共同原始祖先可能广泛分布于中国、朝鲜和日本等东亚地区,约在4.9—6.5百万年前的上新世开始分化,系统发育过程比较适合离散假说。

Molecular phylogeny of the genus Odontobutis based upon partial sequences of mitochondrial 12S rRNA genes

The Odontobutis are valuable small freshwater fishes restricted to the East Asia,but their specific validities and phylogeny has been controversial for a long time.To determine interspecific relationships and evolution of the genus Odontobutis,partial sequences of mitochondrial 12S rRNA genes of all putative species of Chinese Odontobutis fishes(O.sinensis,O.haifengensis,O.yaluensis,and O.potamophila) were sequenced and subjected to phylogenetic analysis with the inclusion of two Japanese species(O.obscura and O.hikimius) and available taxa from Eleotridae obtained from GenBank.The resultant mitochondrial DNA sequence were 690bp long with 34 indels,of which 258 sites were variable and 201 sites were parsimony-informative,and average transition/transversion ratio was 3.0,suggesting that 12S rRNA gene was a suitable molecular marker to be used in studying the interspecies relationships within Odontobutis species.The genus Odontobutis formed a monophyletic group with 100% bootstrap support,and p-distance model-based pairwise genetic distances within each putative species ranged from 0.000-0.024,and those among the six Odontobutis species were between 0.058 to 0.133,which agree with Wu's taxonomic treatment of the genus,i.e.,that O.obscura and O.sinensis were different species,and there were 4 species of Odontobutis in China.In phylogenetic tree,while O.haifengensis and O.potamophila were closely related,and O.hikimius is sister group,and the phylogenetic relationships among the remaining taxa of the genus were not well resolved.As Chinese Ondontobutis had not been sampled extensively and intensively in the present study,whether there are new Odontobutis species or not yet to be further studied.Chinese species and Japanese taxa of the genus Odontobutis were not resolved as monophylogentic group respectively,it is deduced that the common ancestors of the genus Odontobutis might be widely distributed in China,Korea peninsula and Japan,diverged from 4.9 to 6.5 million years B.P.in middle Pliocene,and their phylogenetic process might be explained by vicariant hypothesis.