基于Cyt b基因序列研究6种裸胸鳝属鱼类的进化关系

Phylogenetic relationships of 6 species in Gymnothorax based on sequences of cytochrome b gene

为探讨中国南海裸胸鳝属(Gymnothorax)鱼类系统发育关系,采用PCR扩增产物克隆到T载体后进行序列测定,获得黄边裸胸鳝(Gymnothorax flavimarginatus)、斑点裸胸鳝(G.meleagris)、波纹裸胸鳝(G.undulatus)、云纹裸胸鳝(G.chilospilus)、匀斑裸胸鳝(G.reevesi)5种裸胸鳝的线粒体细胞色素b(cytochrome b,Cyt b)基因全序列1140bp。结合GenBank中的蠕纹裸胸鳝(G.kidako)Cyt b同源序列进行比较分析,结果表明:(1)1140个位点中共有367个核苷酸位点存在变异(32.2%);(2)序列变异的转换/颠换比值平均为3.223;云纹裸胸鳝和斑点裸胸鳝遗传距离差异最大,为0.226;(3)以花鳗鲡(Anguilla marmorata)为外群,采用NJ法和MP法构建系统发育树,在所分析的6种裸胸鳝属鱼类中,斑点裸胸鳝和波纹裸胸鳝聚为一支,位于系统树的基部位置,其余4种聚为另外一支。蠕纹裸胸鳝样本来源于日本海,其余5种裸胸鳝来源于中国南海,从系统树上来看,它们之间并没有明显的地域差异。

In order to study the phylogenetic relationships of the genus Gymnothorax（moray eels） that distributed in South China Sea, polymerase chain reaction was performed, and the amplification products were sequenced by being cloned into PMD18T-vector（TAKARA）. Mitochondrial cytochrome b sequences of five species Gymnothorax （G. flavimarginatus, G. meleagris, G. undulatus, G. chilospilus, and G. reevesi） were obtained. The length of DNA sequences of them was 1 140 bp. In this experiment, MEGA 4.0 Software was used to calculate the genetic distances among six species Gymnothorax（except Cyt b sequences of G. kidako obtained from GeneBank）. The results were as follows： firstly, there were 367 nucleotide sites substituted（32.2%） in 1 140 bp sites; secondly, the transition/transversion ratios of the sequence substitutions of six species Gymnothorax ranged from 2.013 to 6.019, and the average of value was 3.223. The highest comparatively substitution occurred between G.chilospilus and G.meleagris （0.226）. Finally, the NJ tree and the MP tree Clustering maps showed that the genetic differentiation of G.meleagris and G.undulatus was in the same branch, and the genetic differentiation of four species @mnothorax was in another branch.