我国草鱼野生群体D-Loop序列遗传变异分析

摘要

In this study we analyzed the genetic variations in the mtDNA D-Loop sequences of eight wild populations of grass carp (Ctenopharyngodon idella) including six populations (Hanjiang, Wujiang, Jiujiang, Shishou, Mudong, and Wanzhou) from the Yangtze River, the Zhaoqing population from the Pearl River, and the Nenjiang population from Heilongjiang River. A total of 34 variable sites and 34 haplotypes were detected in 424 individuals, and the haplotype diversity ranged from 0.474 to 0.708 among the eight populations. The pairwise population K2P genetic distances were between 0.0020 and 0.0049. The genetic distance between the three populations from the lower reach of the Yangtze River was the closest and their genetic differences were insignificant (P>0.05). The Zhaoqing population also showed a close genetic distance with the three populations from the lower reach of the Yangtze River;and it did not have signifi-cant genetic differences compared to the Jiujiang population (P>0.05). The Nenjiang population displayed a close ge-netic distance with the two populations from the upper reach of the Yangtze River. The genetic difference between the Nenjiang population and the Wanzhou population (P>0.05) was insignificant. Furthermore we observed an extreme sig-nificant correlation between the genetic distance and the geographic distance (P<0.01). The AMOVA analysis suggested that there were highly significant differences between populations (P<0.01), and that the genetic variation among dif-ferent watersheds in China accounted for 26.24%of the total variation. The haplotypes divided into two major branches which exhibited remarkable evolutionary differences (FST=0.644, P<0.01), and this branching might originate in the late Pleistocene.%利用线粒体DNA的D-Loop区序列,对来自长江水系(邗江、吴江、九江、石首、木洞和万州)、珠江水系(肇庆)和黑龙江水系(嫩江)的8个草鱼野生群体开展了遗传变异分析。在424尾鱼中检测到34个变异位点,34个单倍型,单倍型多样性介于0.474—0.708。群体间Kimura双参数遗传距离介于0.0020—0.0049。长江下游3个群体间遗传距离最近,遗传分化不显著(P>0.05)；肇庆群体与长江上游3个群体遗传距离较近,与九江群体遗传分化不显著(P>0.05)；嫩江群体与长江上游2个群体遗传距离较近,与万州群体遗传分化不显著(P>0.05)。遗传距离与地理距离存在极显著正相关(R=0.61, P<0.01)。分子方差分析显示,不同流域间遗传变异占总变异26.24%,差异极显著(P<0.01)。34个单倍型分为2个分支,分化极显著(FST=0.644, P<0.01),推测分化时间为第四纪更新世纪晚期。