Species identification and phylogenetic relationship in Siganidae based on DNA barcoding

In order to establish a rapid and convenient method for fish species identification of Siganidae, we obtained 46 COⅠ genes from 10 species and downloaded 27 COⅠ genes from 12 species from BOLD and GenBank to study the COⅠ gene's genetic composition, intraspecific and interspecific genetic distance, codon characteristics and molecular phylogenetic tree. The results show that the average base composition of 73 COⅠ genes was T: 28.9%, C: 28.7%, A: 24.6% and G: 17.8%. The content of G+C (46.5%) was lower than the content of A+T (53.5%) and the base composition showed obvious bias. The average interspecific genetic distance was 0.098, which was 49 times the length of the genetic distance within the species (average: 0.002). The phylogenetic tree reveals that Siganus unimaculatus and S. vulpinus clustered into one branch among 19 species of basket fish. The other 17 species (89.5%) clustered in monophyletic groups at genus level. It is shown that the technology of DNA barcoding can be used for fish species identification of Siganidae.