| Abstract: Studies on genetic variation in marine organisms are an important component of successful and sustainable management of marine biology resources. In this paper, genetic variatiaon of 6 populations of Octopus ocellatus in China coastal water were investigated by applying mitoch -ondrial gene(COI) sequencing technology. Results showed that ,Compared with other cephalopod species, Octopus ocellatus showed higher genetic diversity in populations. 42 polymorphic sites were detected in 654bp aligned sequence, which reprented for 6.42% of the total length of sequenced COI gene. 23 hapotypes were detected out of 60 individuals from 6 populations. The hapotype diversity (HD) , mean nucleotide diversity(pi) and average number of nucleotide differences reached 0.200-0.867, 0.0003-0.0097, 0.200-6.311, respectively. Molecular variance analysis revealed strong genetc sturcture in 6 Octopus ocellatus populations（p﹤0.05）. A pattern of genetic-isolation-by-distance, comforming to Stepping Stone Model, was detected when plotting Nm against geographic distance.UPGMA tree constructed showed that 6 Octopus ocellatus populations can be divided into two lineages, one consisiting of Dalian, Qingdao,Lianyungang plulation and the other consisting of other 3 populations, and between which, 20 fixed nucleotide sites and 2 fixed amino acid sites subtitute along the gene sequence and coded protein were detected. The Fst between them reached 0.8602 (p﹤0.01) and the Nm between them turned out to be much lower than 1. AMOVA test, which showing 12.72% of the genetic variation lies within populations and 87.28% lies between populations, further suggested the genetic differentiation between the two lineages. These findings in the aspect of genetic variation of Octopus ocellatus will contribute to better exploitment and refined management of this precious cephalopod resources along the coast of China in future. |
