中沙和南沙群岛密点胡椒鲷的种群分析

Population genetic structure of coral reef species Plectorhynchus gaterinus in Zhongsha and Nansha Islands

对中国南海中沙群岛和南沙群岛采集的2个珊瑚礁栖性鱼类密点胡椒鲷(Plectorhynchus gaterinus)群体共19尾的mtDNA控制区核苷酸序列进行了扩增分析,获得了长度为510bp的同源序列,2个群体中共检测到变异位点31个,占全部序列的6.08%,2个群体共检测到15种单倍型。AMOVA分析表明,群体间的遗传变异仅占总遗传变异的1.97%,而98.03%的遗传变异源于群体内。2个密点胡椒鲷群体间的分化指数(Fst)仅为0.012,群体分化程度很低。以线粒体DNA控制区序列构建的NJ树揭示,2个群体的个体基本是随机交叉聚类,各群体内的个体均未单独成群,不能形成明显的类群分支。以上结果表明,密点胡椒鲷群体间遗传相似性较大,且存在较强的基因交流,尽管中沙和南沙群岛地理隔离明显,距离较大,但两个群岛的密点胡椒鲷地理分化不明显,仍可认为是一个大的种群。

The population genetic structure and the dispersal ability of Plectorhynchus gaterinus from South China Sea were examined with a 510 bp segment of mtDNA control region. A total of 19 individuals were collected from 14 coral reefs in Zhongsha and Nansha archipelagos and 15 haplotypes were obtained. There were 31 variation sites in those gene fragments, and the mutation rate was 6.08%. Analysis of molecular variance indicated that large mtDNA differentiation occurred within populations （98.03%）,and only 1.97%occurred among populations. The calculation of genetic parameters suggested that genetic differential index （Fst） between populations was 0.012,and the degree of genetic differentiation was low. Molecular tree constructed by NJ method showed the individuals of the different stocks could not be clustered as one independent group and intermixed together. These results indicated that great gene flow existed among populations and the genetic diversity between populations was at quite lower levels.Although the water reaches a depth of thousands of meters and large scales distances among coral reefs in these archipelagos,the geographic subdivision of the Plectorhynchus gaterinus in Zhongsha and Nansha archipelagos was indistinct,suggested that they maybe still belong to one single population.