基于COⅠ基因对南海鱼类鉴定的可行性分析

Feasibility analysis of fish identification in South China sea based on COⅠgene

为研究DNA条形码技术在南海海域鱼类分类鉴定中的可行性,采集了南海6目28科43属65种鱼类进行COⅠ基因序列扩增,获得序列与NCBI数据库进行比对,结合形态学信息,对鱼类分类鉴定进行分析.利用MEGA5.0软件计算各物种序列信息、遗传距离以及构建分子系统进化树,结果显示所得65种鱼类COⅠ基因同源序列633 bp,与NCBI数据库比对,可搜索出相似率99%以上的样品,可以鉴定到种的水平.序列中A、T、G、C碱基平均组成为A23.8%、T28.6%、G18.8%、C28.8%.样品种间、属间、科间和目间的遗传距离分别为14.88%、19.09%、23.14%和24.68%,随着分类阶元的升高,物种的平均遗传距离差异越大.构建的系统进化树,科级以下阶元的分类关系与形态分类基本一致,而科级以上阶元的分类关系与形态学分类差别较大,说明COⅠ基因在鱼类分子鉴定上是有效的条形码基因,但在系统进化关系上不一定适用于高级阶元的系统进化分析.

In order to study the feasibility of DNA bar-coding technology in fish identification from the South China Sea,65 species belonging to 43 genera,28 families and 6 orders in the South China sea were collected and the COⅠgene sequence of the species were amplified and determined,all sequences were aligned using BLAST from NCBI database for the species identification combining with the morphological information to identify and classify fishes.The sequence information,genetic distance and molecular phylogenetic tree of each species were calculated uing MEGA5.0 software.The results showed that the homologous sequence of COⅠgene of 65 species were 633 bp.Comparing with the NCBI database,BLAST results with similarity rates of more than 99%can be obtained,which could be identified to species level.The average composition of A,T,G,C were 23.8%,28.6%,18.8%and 28.8%.The genetic distances among species,genera,families and orders were 14.88%,19.09%,23.14%and 24.68%,respectively.With the increasing of taxonomic category,the difference of average genetic distance became larger.In the phylogenetic tree,the species taxonomic relationships below family level were consistent with the morphological classification,while the relationships above family level were quite different from the morphological classification,indicated that the COⅠgene is an effective bar code gene in fish molecular identification,but it is not necessarily suitable for the higher taxonomic level analysis for the molecular phylogenetic studies.