3个地理群体仿刺参D-loop序列的变异及系统发生分析

为研究中国大连(CD)、朝鲜罗津(KN)和俄罗斯海参崴(RV)3个仿刺参群体的遗传结构,实验采用PCR扩增和测序技术,对3个群体共计71头仿刺参的线粒体D-loop序列进行了分析。结果显示,D-loop序列长度为447~465 bp,平均A+T含量(59.2%)显著高于G+C含量;共检测到119个变异位点,多态位点比例为24.24%,其中简约信息位点为53个,共有40种基因型,群体共享基因型7个。遗传多样性参数分析显示,3个群体均显示出较丰富的遗传多样性;分子方差(AMOVA)分析表明,3个群体间遗传分化较弱或只有中度分化,且93.04%的变异来自群体内。CD群体与RV群体之间遗传距离最远,为0.042,KN群体与RV群体之间遗传距离最近,为0.037 4。将本研究所得序列结合GenBank中青岛(QD)和威海(WH)仿刺参的D-loop序列构建系统发育树,QD与WH仿刺参首先聚为一小支,然后与CD群体聚为一大支,KN群体与RV群体聚为独立一支,这一聚类方式符合地理隔离模式。

D-loop sequences variation and phylogenetic analysis in three geographical populations of the sea cucumber Apostichopus japonicus

Mitochondrial D-loop sequences were analyzed to study the genetic structure of the sea cucumber Apostichopus japonicus. In this study, 71 individuals from three natural populations were collected from Dalian, China (CD), Rajin, North Korea (KN) and Vladivostok, Russia (RV). 447-465bp D-loop sequences were obtained using PCR amplification. The mean content of A T (59.2%) was higher than G C. The proportion of polymorphic sites was 24.24%, in which parisimony informative sites were more than 53. Forty haplotypes were identified from 71 samples, among which 7 haplotypes are shared by three populations. Genetic diversity parameters showed high genetic diversity among populations. The fixation indices (FST) of analysis of molecular variance (AMOVA) within populations was 93.04%, which indicates that the genetic differentiation of the three populations were weak or only moderately differentiated. The genetic distances of among-population were 0.0374 (KN and RV) and 0.042 (CD and RV). The molecular phylogenetic tree was constructed with the D-loop sequence of Qingdao (QD) and Weihai (WH) from GenBank with NJ method using software MEGA 4.0. Populations of QD and WH clustered into a small branch then with CD, while KN and RV clustered into other group. The results were consistent with their geographical isolation mode.