长江中游鳊群体的遗传多样性

Genetic diversity of White bream,Parabramis pekinensis from the Middle Yangtze River

采用线粒体DNA(mt DNA)细胞色素b基因(cytb)和控制区序列,分析长江中游宜都、沙市、燕窝、团风等4个产卵场鳊种群的遗传多样性和遗传结构。结果表明:长江中游鳊群体cytb序列共检出82个多态位点,86种单倍型,平均单倍型多样性指数(Hd)和核苷酸多样性指数(Pi)分别为0.930和0.00244;控制区序列共检出变异位点46个,单倍型76种,Hd指数和Pi指数分别为0.972和0.00505;构建的单倍型网络结构和分子方差分析(AMOVA)显示,4个群体的遗传变异绝大部分来自群体内部,群体间无显著遗传分化;群体间的分化指数(FST)、平均基因流(Nm)和平均K2-P遗传距离均表明,4个鳊地理群体间存在广泛的基因交流,未发生明显群体遗传分化;中性检验表明,鳊历史上发生了群体扩张,扩张时间在第四纪冰期后期。

In this study, mitochondrial DNA cytb gene and D-loop sequences were used to inves- tigate the genetic diversity and genetic structure of White bream Parabramis pekinensis populations from 4 major spawning grounds （Yidu, Shashi, Yanwo, Tuanfeng） in the middle Yangtze River. The results showed that 82 polymorphic sites and 86 different haplotypes were identified among mtDNA cytb sequences, and the average haplotype diversity （Hd） and average nucleotide diver- sity （ Pi ） were 0.930 and 0.00244, respectively. Forty six polymorphic sites and 76 different hap- lotypes were identified among mtDNA D-loop sequences, and the Ha and Pi values were 0.972 and 0.00505, respectively. Analysis of molecular variance （AMOVA） and haplotype network structure suggested that most of the genetic variation in the four populations was within groups, with no significant genetic divergence among populations. Meanwhile, pairwise average Kinura 2- parameter distances, the FST value and Nm value also revealed that genetic exchange existed among populations. The neutral test showed that historical population expansion occurred in P. pekinensis, and the expansion appeared in the late Quaternary glacial period.