Application of COI-based DNA barcoding in Gymnothorax Species in South China Sea

In order to explore the phylogenetic relationships of gymnothorax species in South China Sea,504 bp length fragments of mitochondrial cytochrome oxidase subunit Ⅰ gene from 6 species of genus Gymnothorax (G. flavimarginatus,G.reticularis,G.melanospilus,G.rueppeliae,G.fimbriatus,G. favagineus) in South China Sea were sequenced. Based on the phylogenetic analysis of the homologous sequences of COⅠ gene sequences of Gymnothorax from 3 species in South China Sea and 1 species in Japan downloaded from GenBank,neighbor-joining (NJ ) and maximum parsimony (MP) methods were used to construct molecular phylogenetic trees. The results indicated that there were 187 nucleotide sites substituted(37.1%) in 504 bp sites;the average value of transition/transversion ratios was 1.5;nucleotide sequence divergence was only 0.20 % between G.fimbriatus and G. favagineus,which supported the opinion that G.fimbriatus and G. favagineus might be synonyms; the NJ tree and the MP tree Clustering maps showed that the genetic differentiation of G.reticularis and G.kidako was in the same branch,and the genetic differentiation of eight species Gymnothorax was in another branch.