基于线粒体COI基因的部分鲇形目鱼类系统发育研究

本文选择COI基因片段作为分子标记,对部分鲇形目鱼类(Siluriformes)进行系统发育研究。应用通用引物PCR扩增得到13种鲇形目鱼类的134条COI基因,并与Gen Bank中获得15种鲇形目鱼类的51条COI基因进行比对分析。结果显示:鲇形目鱼类COΙ基因存在碱基插入缺失现象较少,为越南隐鳍鲇(Pterocryptis cochinchinensis)、丝尾鳠(Hemibagrus wyckioides)和黄颡鱼(Pelteobagrus fulvidraco)3种共计5个位点;平均碱基含量A+T(55.5%)显著高于G+C(44.5%)。利用Kimura’s 2-parameter计算28个物种的种间平均遗传距离为0.195,23个物种的种内平均遗传距离为0.006。系统发育树的分析结果表明,Neighbour-Joining(NJ)树较Maximum Likelihood(ML)树更为适合鲇形目鱼类的遗传发育分析;COI基因在科及其以下水平的系统进化关系与传统分类方法所认同的结果一致性较高,达到82.9%以上;在目水平的一致性的可信度较低,仅为71%;半鲿属聚为单系类群,黄颡鱼属、属和拟鲿属三者聚为一支,黄颡鱼属与拟鲿属的亲缘关系较近。

Phylogenetic analysis of catfish (Siluriformes) based on the mitochondrial COI gene

Catfish, important economic fishes, account for about one-third of the freshwater fishes globally, and are widely distributed with abundant species and population structures in China. Owing to limited bones in the muscle and good taste, catfishes are widely consumed and occupy an important position in the aquatic products market. In this study, using the COI (cytochrome oxidase subunit I) gene fragment as a molecular marker, phylogenetic analyses were carried out on some catfish species. A total of 134 sequences of 13 species of catfishes were amplified using universal primers, and the results were compared with 51 other sequences belonging to 15 species of catfishes obtained from GenBank. The results showed that Pterocryptis cochinchinensis, Hemibagrus wyckioides, and Pelteobagrus fulvidraco included five insert-deletion sites. The average base A+T (55.5%) was significantly higher than that of G+C (44.5%). The average genetic distance of 28 pairwise and 23 within species were determined as 0.195 and 0.006, respectively using Kimura''s 2-parameter (MEGA6.0). The phylogenetic tree analysis showed that a neighbor-joining tree was more suitable than the maximum likelihood tree for the genetic analysis of the catfish species. According to neighbor-joining tree for all 185 sequences of catfishes, the consistency with traditional taxonomy on family levels and below was higher (82.9%) than that of order levels (71%). Samples of each Hemibagrus species formed highly supported monophyletic groups. The neighbor-joining tree showed that species of Pelteobagrus, Pseudobagrus, and Leiocassis come from the same branch, and the Pelteobagrus species has a were closer relationship with Leiocassis. The results of this study showed that the COI gene could be used as a molecular assistive tool for the identification of catfish species, and could also be applied to molecular phylogenetic relationships. The results effectively expanded the species classification information of catfishes, and provided necessary evidence for traditional taxonomy.