基于线粒体控制区的江苏湖鲚群体遗传多样性和遗传结构分析

Genetic diversity and genetic structure of Coilia nasus taihuensis populations in Jiangsu Province based on mtDNA control region sequences

为掌握江苏省重要湖泊湖鲚(Coilia nasus taihuensis)群体的遗传多样性和遗传结构,利用线粒体控制区(D-loop)全序列分析了6个湖泊(太湖、滆湖、高邮湖、白马湖、洪泽湖和骆马湖)湖鲚野生群体的遗传多样性水平和群体分化情况。结果表明,6个群体共214尾样本的D-loop序列中,共发现103个变异位点,92种单倍型。6个群体的单倍型多样性为0.726~0.951,核苷酸多样性为0.00552~0.01036,6个群体整体的单倍型和核苷酸多样性分别为0.857和0.00729,表明湖鲚群体的遗传多样性较高,且符合高单倍型多样性和低核苷酸多样性特点。分子方差分析(AMOVA)结果表明,群体间变异百分比为6.20%,群体内变异百分比为93.80%,说明遗传变异主要来自群体内部。群体总的遗传分化系数(F_(st))为0.06199(P<0.01),两两群体间的F_(st)显示,滆湖群体与其他群体间存在极显著的遗传分化(P<0.001),而其他群体间无显著分化(P>0.05)。单倍型分子系统进化树和网络进化图显示,6个群体的单倍型形成了2个谱系,但谱系组成与群体地理分布无相关性。中性检验分析结果显示,湖鲚群体进化过程中经历过种群扩张,扩张时间大约发生在0.089~0.160百万年前。研究结果表明,湖鲚群体具有较高的遗传多样性,滆湖群体与其他群体具有极显著的遗传分化,且拥有多个独享单倍型,应将滆湖群体单独作为一个管理单位,其他5个群体作为一个整体进行管理和利用。

Coilia nasus taihuensis is the dominant species in freshwater lake fish community of the lower reaches of the Yangtze River and Huaihe River,and it is also an important fishing target.In order to better understand the genetic diversity and genetic structure of C.nasus taihuensis populations in freshwater lakes,we analyzed the genetic variation of mitochondrial DNA loop region among six wild lake populations(Ge Lake,Tai Lake,Gaoyou Lake,Baima Lake,Hongze Lake and Luoma Lake)of C.nasus taihuensis in Jiangsu Province.By means of PCR amplification and sequencing,the full length of D-loop sequences were obtained and then used for genetic diversity and genetic structure analysis.A total of 103 variable sites and 92 haplotypes were detected in 214 individuals.The haplotype diversity and nucleotide diversity of six populations varied from 0.726 to 0.951,from 0.00552 to 0.00552,respectively.Meanwhile,the haplotype diversity and nucleotide diversity of total populations were 0.857 and 0.00729,respectively.Results suggested that the haplotype diversity of C.nasus taihuensis was high,while the nucleotide diversity was low.AMOVA analysis indicated that 6.20%of the molecular variation occurred between populations,and 93.80%occurred within populations,suggesting that great genetic differentiation existed among certain populations.The genetic differentiation index(F_(st))value of total populations was 0.06199(P<0.01),and the pairwise F_(st)values among populations indicated that there was significant genetic differentiation between Ge Lake population and the other five populations,and there was no significant genetic differentiation among the five populations.The neighbor-joining phylogenetic tree and parsimony network of haplotypes indicated that individuls of C.nasus taihuensis were divided into two lineages without correlation with geographical populations.The neutrality tests suggested C.nasus taihuensis population had undergone population expansion in evolutionary history,and the population expansion appeared in 0.089-0.16 million years ago.The research results showed that the genetic diversity of C.nasus taihuensis was abundant in Jiangsu Province.The Ge Lake population owned multiple peculiar haplotypes,and there were significant genetic differences between Ge Lake population and the other five lake populations.So,the Ge Lake population should be managed as an independent unit,and the other five populations should be managed and utilized as a whole unit.