基于Cyt b 基因序列的中国沿海4个长蛸(Octopus variabilis)群体的种群遗传结构分析

采用线粒体Cytb基因测序技术研究了我国不同海域4个长蛸(Octopus variabilis)群体的种群遗传结构。结果表明,232bp的Cytb基因片段在4个群体90个个体中共检测到38个多态位点、12个单倍型,单倍型多样性指数H达0.854±0.015,核苷酸多样性指数Pi达0.059±0.005,平均核苷酸多样性指数K达13.526,显示出较高的遗传变异。种群遗传结构分析表明,4个群体间均存在极显著的遗传分化(P<0.01),除大连与青岛两群体间外,其它两两群体间的基因流均小于1。聚类分析表明,4个群体明显分化为三大类群,一个类群由大连和青岛群体组成,一个由温州群体组成,另一个由东山群体组成;遗传距离分析表明,东山类群与其它类群之间可能为亚种水平的分化,而其它类群之间仍为种内群体间分化。长蛸这种种群遗传结构形成原因可能与其较弱的种群扩散能力有关,另外冰川期地理历史因素及我国海域的洋流作用可能也参与了长蛸种群遗传结构的形成。

GENETIC STRUCTURE IN 4 OCTOPUS VARIABILIS POPULATIONS FROM CHINA COASTAL WATERS BASED ON MITOCHONDRIAL Cyt b GENE SEQUENCE

Genetic structure in 4 Octopus variabilis populations from China coastal waters was investigated using mitochondrial cytochrome b gene (Cyt b) sequence. Results showed that, the aligned 232bp segment of the Cyt b gene sequence defined 38 polymorphic sites and 12 haplotypes in the ninety individuals of the four O. variabilis populations. The haplotype diversity (H) reached 0.854±0.015, the mean nucleotide diversity (P_i) reached 0.059±0.005, and the average number of nucleotide differences (K) reached 13.526. Genetic structure analysis showed that, significant genetic differentiation were presented among the four O. variabilis populations (P<0.01). Most pairwise gene flow values between populations were less than 1 except that between Dalian and Qingdao populations. Three distinct clades were detected in four O. variabilis populations based on UPGMA phylogenetic analysis, with one clade composed of the two populations of Dalian and Qingdao, one composed of Wenzhou population, and one composed of Dongshan population. Genetic distance analysis suggested that the differentiation among Dongshan and other clades might reach the level of sub-species, while the differ-entiation among other clades should be within the inter-population level. The divergence of populations might be resulted from low dispersal ability of O. variabilis at both larva and adult stage. In addition, demographic historical accidence and ocean currents may play important roles in the formation of population genetic structure in O. variabilis.