DNA条形码技术在鲻科鱼类鉴定中的应用

Application of DNA Barcoding in Classification of Mugilidae Fishes

本研究选用DNA条形码的通用基因片段,采用特异性扩增测序及与GenBank已有序列结合分析的方法,进行了鲻科（Mugilidae）6属17种鱼类的COI基因片段的序列比较、分子树构建和系统进化研究。研究表明,在所得的17种鲻科鱼类共有的555bp COI基因片段中平均GC含量为46.9%。其中,第二密码子位点含量最高（49.8%~56.2%）,平均54.9%;第一密码子变化范围最大（31.9%~48.6%）,平均42.9%;第三密码子差别不显著（42.5%~43.4%）,平均42.7%。依据Kimura-2-parameter模型（K2P）,17种鲻科鱼类种内遗传距离的平均值为0.004 5,种间遗传距离为0.191,是种内遗传距离的42倍。在分子系统树上,所有物种均呈单系,5属为独立分支,只有隶属于梭属（Liza）的尖头梭（Liza tade）与莫鲻属（Moolgarda）聚类,表现出与传统形态学分类不一致的结果。本研究结果验证了线粒体COI基因作为DNA条形码对鲻科鱼类进行物种鉴定的有效性,可用于辅助探讨鲻科科下属、种分类阶元系统发育问题。

A total of 72 individuals from 17 species pertaining to 6genera of Mugilidae were barcoded with COI gene which were sequenced and compared with each other.Our results indicated that the average GC content of the gene accounted for 46.9%.The GC content of codons was 42.9%（31.9%~48.6%）at the firstnucleotide position,54.9%（49.8%~56.2%）at the second,and 42.7%（42.5%~ 43.4%）at the third.The average Kimura-2-parameter（K2P）distances within-species and pairwise-species were 0.45%and 19.1%,respectively.The K2 Pdistance of pairwise-species was 42 times of that within-species.According to the maximum parsimony and neighbor-joining trees for all 72 sequences,17species,all individuals of each species formed a strong monophyletic group.However,Liza tade belonging to Liza genera clustered with Mologarda genera,which was different from the morphological characters.Our research demonstrated that the COI barcoding was a useful tool for fish species identification,which may also afford auxiliary discussions about the phylogeny of Family Mugilidae