脊尾白虾3个野生群体线粒体COI基因的遗传多样性及其系统发育分析

The genetic diversity and phylogenetic analysis of COI gene in mitochondrial DNA of three populations of Exopalaemon carinicauda

采用PCR扩增技术对脊尾白虾的莱州湾、海洲湾、象山湾的3个野生群体共计62个个体的线粒体COI基因片段进行扩增和测序,获得长度为658bp核苷酸序列。62条序列T、C、A、G和A+T的平均含量分别为31.53%、22.63%、27.30%、18.53%和58.83%,A+T含量显著高于G+C含量,这一结果与甲壳类、双壳贝类等的COI线粒体基因片段中的观察结果相似。通过统计变异位点、核苷酸多样性指数和平均核苷酸差异数进行基因序列变异分析。AMOVA分析表明,3群体间总遗传分化系数Fst=0.3611(P<0.01),群体间存在较高的遗传分化,其中象山湾群体与莱州湾群体之间的遗传分化系数最高,莱州湾群体与海洲湾群体之间的遗传分化系数最低。另外用MEGA4.0软件中的NJ法构建分子进化树,同时由NCBI下载同源序列,探讨了长臂虾亚科几个种的系统进化关系,用NJ法构建的系统树显示,脊尾白虾不同单倍型先与长臂虾属和小长臂虾属聚为一支,然后与沼虾属聚为一支。

Fragments from mitochondrial gene of Eacopalaemon carinicauda sampled from three sites （Haizhou Bay, Xiangshan Bay, and Laizhou Bay） were amplified and se- quenced. Sixhundred and fifty eight bp COl fragments were obtained. The T,C, A,G,and A＋ T mean contents in those fragments were 31.53% ,22.63% ,27.30% ,18.53%, and 58.83% respectively,which were similar to the results of crustaceans and bivalves. Variable sites, nucleotide diversity and average number of nucleotide differences were calculated to analyze the gene sequence variation. The fixation indices（Fst）analyzed by Analysis of Molecular Variance （AMO- VA） of Arlequin Version 3.1 totaled to 0. 361 I（P〈0.01） ,indicated significant genetic fixation among three populations. Among them, the genetic differentiation between Xiangshan Bay and Laizhou Bay was the highest,the lowest between Laizhou Bay and Haizhou Bay. The molecular phylogenetic tree constructed by NJ method using software MEGA 4.0 to study molecular phy- logeny of several species of the by Palaemonidae. The phylogenetic tree showed that different haplotypes of E. carinicauda were more closely related to Palaemon and Palaemonetes than to Macrobrachium.