广东和广西地区野生文蛤的遗传多样性

Genetic diversity of seven wild populations of Meretrix meretrix

以产于广东和广西两省海区的7个野生文蛤(Meretrixmeretrix)群体为实验对象,结合形态特征、生长性能分析与核基因DNA的RAPD标记,对其遗传多样性进行系统研究,结果表明,在贝壳形态方面,广西各群体的平均壳长、平均壳高、平均壳宽、壳重和总重都明显大于广东群体(P<0.01);在生长性能方面,广西群体的壳宽系数、壳重指数、肥满度指数也高于广东群体(P<0.01)。RAPD分析共筛选了120个随机引物,其中,61种引物呈阳性反应,至少10种引物的扩增带表现出丰富、稳定的多态性。本实验用10个随机引物扩增出78个位点;平均每个引物在每个个体扩增出3.32条带。其中,引物8747对汕尾群体无扩增带。各群体的多样性指数为0.2088～0.2594,多态位点比例为85.71%～94.74%。群体间的遗传距离为0.0271～0.2195,相对而言,地理位置相隔越远,遗传距离越大。

The wild samples of Meretrix meretrix were collected from Dongxin, Beihai and Shankou in Guangxi Province, and Xuwen, Namsan, Yangjiang and Shanwei in Guangdong Province, respectively. For each population, 200 individuals were employed, body weight 3.9-87.8 g and 1-4 years old. The comparison of their morphological characters was studied, and RAPD were used to analyze their genetic diversity. The results show that the mean shell length, shell height, shell width, shell weight and total weight of Guangxi population are obviously larger (P<0.01) than those of Guangdong population; The index of shell width and shell weight, and the condition factor of Guangxi population are also higher (P<0.01) than those of Guangdong population. RAPD analysis indicates that there are 61 primers positive out of 120 random primers, and 10 primers, at least, reveal clear and stable polymorphisms. Ten primers used in the analysis totally amplified 78 loci; each primer averagely amplifies 3.32 DNA bands in every individual. The primer 8 747 did not amplify any DNA band in Shanwei population in Guangdong. The rate of polymorphisms of amplified DNA band in all populations ranges from 85.71% to 86.67%; and the Shannon index varies between 0.208 8 and 0.259 4. The genetic distance among the populations ranges from 0.027 1 to 0.219 5. Relatively speaking, the more the geographic distance between populations, the bigger the genetic distance.