鲳亚目鱼类线粒体16S rRNA基因序列变异及其分子系统进化关系

Mitochondrial 16S rRNA sequence variation and molecular phylogenetic relationships of Stromateoidei fishes(Teleostei:Perciformes)

为探讨鲳亚目鱼类的系统进化关系,通过测定中国沿海8种鲳亚目鱼类的线粒体16SrRNA基因部分序列,并结合GenBank上其他鲳亚目鱼类的同源序列,对其序列变异和分子系统进化树进行分析。结果表明,鲳亚目5科13属32种鱼类的16S rRNA基因序列的碱基组成为T 22.2%、C 24.5%、A 30.0%、G 23.3%;科间遗传距离为0.060～0.120,属间遗传距离为0.009～0.125,种间遗传距离为0.000～0.163;长鲳科位于系统进化树的基部,鲳科的鲳属处于系统进化树的顶端,无齿鲳科、方尾鲳科、双鳍鲳科与鲳科的低鳍鲳属和真鲳属聚类。结合形态学研究结果,认为:长鲳科是鲳亚目中最先分化的原始单系群;无齿鲳科和方尾鲳科为单系群,它们与非单系群的双鳍鲳科有较近的亲缘关系;鲳科为并系群,内部存在与地理区系相对应的2个分支,提示了该科鱼类早期的分化模式。同时,也对16S rRNA基因在鲳亚目鱼类系统进化研究中的适用性进行了剖析。

The suborder Stromateoidei（Teleostei：Perciformes）currently comprises 6 families,16 genera,and about 70 species.They occur worldwide in coastal and oceanic waters of tropical to temperate regions.Fishes of Stromateoidei are one of the most economically important in the world.However,due to the high diversity of morphological characters,the taxonomic status and phylogenetic relationships of Stromateoidei have been long confused.In this study,the mitochondrial 16S rRNA gene fragment of 8 species of Stromateoidei collected from Chinese coastal waters,were amplified using PCR techniques.The homologous sequences of other Stromateoidei fishes from GenBank were also included in this study.The genetic information indexes,including base composition,sequence variation and Kimura-2 parameter genetic distance were examined.Phylogenetic trees were constructed based on Neighbor-Joining（NJ）and maximum-parsimony（MP）methods.Total of the 458 aligned base pairs,with 119 variable sites,114 parsimony informative sites,5 singleton sites,were detected in the analyzed Stromateoidei fishes（5 families,13 genera,and 32 species）.The average contents of T,C,A and G were 22.2%,24.5%,30.0% and 23.3% respectively for 16S rRNA sequence analysis.The genetic distances among families,genera and species range from 0.060 to 0.120,0.009 to 0.125,and 0.000 to 0.163 respectively.The phylogenic analysis placed Centrolophidae in the most basal position of the Stromateoidei,Pampus（Stromateidae）at the top of the two trees,Ariommatidae,Tetragonuridae,Nomeidae in a sister position to the clade of Peprilus and Stromateus（Stromateidae）.Based on the results of molecular analysis and morphology data,several conclusions were drawn as follows：（1）family Centrolophidae,which was early diverged,is the most primitive monophyly group in the suborder Stromateoidei;（2）Ariommatidae,Tetragonuridae are the two monophyletic groups,which showed close relationship with the non-monophyletic group of Nomeidae;（3）the paraphyletic group of Pampus is the most recently diverged species,which is in accordance with the fact that it is also the most flourishing genus in Stromateoidei.There are two parallel evolutionary clades in genus Pampus.The species within the two clades seem to be relevant to their biogeographic distributions.In addition,the application of 16S rRNA gene for phylogenetic study in the suborder Stromateoidei is discussed in this study.