基于线粒体DNA序列探讨斑头鱼分类地位

测定了斑头鱼Agrammus agrammus和大泷六线鱼Hexagrammos otakii的线粒体COⅠ、Cyt b和16S rRNA基因的部分序列,结合从GenBank中获得的六线鱼属3种的同源序列,以单鳍多线鱼Pleurogrammus monopterygius为外群,运用邻接法(NJ)、最大简约法(MP)和贝叶斯法(BI)构建了分子系统树。同时联合了3个基因片段序列,运用贝叶斯联合模型综合探讨了六线鱼类的系统发育关系。结果显示:除16S rRNA基因外,其余2个基因片段以及联合模型所构建的系统树拓扑结构完全一致,即斑头鱼与大泷六线鱼亲缘关系最近,应归为六线鱼属,拉丁学名应为Hexagrammos agrammus。Cyt b基因片段序列分析结果显示,斑头鱼和大泷六线鱼分歧时间约为175万年。结合形态学研究资料,支持将斑头鱼归为六线鱼属的观点,斑头鱼和大泷六线鱼亲缘关系最近,属于六线鱼科中分化较晚的种类。

STUDY ON THE THE TAXONOMIC OF AGRAMMUS AGRAMMUS BASED ON MITOCHONDRIAL GENE FRAGMENTS

The mitochondrial COⅠ, Cyt b and 16S rRNA gene fragments of Agrammus agrammus and Hexagrammos otakii were amplified and sequenced in this study. Combined with the 3 homologous sequences of 3 species of Hexagrammos available from GeneBank, the variations of their sequences were analyzed and the phylogenetic trees were reconstructed with neighbor-joining (NJ), maximum-parsimony (MP) and bayesian inference (BI) methods, using Pleurogrammus monopterygius of Hexagrammidae as outgroup. Meanwhile the combined data of 3 genes sequences was studied by Partitioned Bayesian Analyses in order to clarify their phylogenetic relationships. The results showed that: A. agrammus was most closely associated with H. otakii supported by phylogenetic tree of COⅠ, Cyt b and combined data. A. agrammus and Hexagrammos agrammus should be a same genus. The estimated time of divergence between A. agrammus and H. otakii was about 175 ten thousand years based on Cyt b gene sequences. Coupled with morphological data, the conclusion was that A. agrammus and H. otakii were sister species, which belonged to sympatric speciation and latest speciation in fishes of the family Hexagrammidae.