近江牡蛎两个野生种群的遗传多样性分析

采用RAPD分子标记和rDNA-ITS1序列分析了近江牡蛎Crassostrea rivularis湛江官渡和阳江程村野生种群的遗传多样性。12个RAPD引物共扩增出8838条片段,157个位点,平均每个引物可产生13个位点,片段长度在200～2200bp之间。湛江种群和阳江种群的多态位点比例分别为89.62%和89.57%,遗传多样性指数分别为0.4170和0.4334。种群间平均遗传距离为0.0327,平均遗传相似性为0.9681,平均遗传分化系数为0.0437。得到近江牡蛎18S、5.8S部分序列和ITS1全部序列,其中ITS1序列片段长度为478～485bp,共有11个变异位点,两个为转换(A/G),其他为插入/缺失(A/-、T/-)。湛江和阳江种群各获得8个单倍型,其中有一个单倍型为两个种群共享。两个种群的CG碱基平均含量较高,分别为58.29%和58.41%。种群间的遗传分化系数0.0254。结果说明,近江牡蛎湛江种群和阳江种群间具有较高的遗传多样性和较低的遗传分化。

Genetic Diversity of Two Wild Populations of Oyster Crassostrea rivularis

Genetic diversity of two populations of oyster Crassostrea rivularis sampled respectively from Zhanjiang and Yangjiang was studied by using RAPD markers and rDNA-ITS1 sequence comparison. The results were as follows: (1) Twelve RAPD primers totally amplified 157 loci and 8838 bands,with the size ranging from 200 to 2 200 bp. The percentage of polymorphic loci and the average genetic diversity index were 89.62% and 0.4170 in Zhanjiang population, and there were 89.57% and 0.433 4 in Yangjiang population. The average genetic identity, genetic distance and genetic differerntiation index between the two populations is 0.968 1, 0.032 7 and 0.043 7, respectively. (2) The ribosomal internal transcribed spacer 1 segment was studied by PCR. The product contains partial sequence of 18S gene and 5.8S gene, and complete sequence of ITS1, containing the primers. The length of ITS1 segment varies from 478 bp to 485 bp with 11 variable sites, including two transition sites (A/G) and nine insertion /deletion sites (A/-,T/-). Eight haplotypes were observed in two populations, of which one haplotype was shared. The average GC content of ITS1 was 58.29% in Zhanjiang population and 58.41% in Yangjiang population, respectively. The genetic differerntiation index between the two populations was 0.025 4. The results indicated that the two populations of C. rivularis had high genetic diversity and low genetic differentiation.