长江中下游褶纹冠蚌10个群体COⅠ基因序列变异分析

Sequence Variation of COⅠ Gene in Ten Populations of Cristaria plicata from the Middle and Lower Yangtze River

以线粒体COⅠ基因为分子标记,对长江中下游褶纹冠蚌(Cristaria plicata)10个群体共200个个体的遗传多样性进行了研究。获得了620bp的同源序列,A+T的平均含量为60.1%,明显高于G+C含量(39.9%),有105个核苷酸变异位点,占全部碱基数的17%,转换和颠换之比达到8.7,检测到了58个单倍型(GenBank登录号:EU698893～EU698950),Hap-5是主体单倍型,占总个体数的41%。褶纹冠蚌鄱阳湖群体(PY)平均核苷酸差异数和核苷酸多样性指数均最高,分别为25.426和0.04101,太湖群体(TH)和衢州群体(QZ)遗传多样性参数较低。基于群体间遗传距离构建的NJ系统树中,洪泽湖内的3个群体与巢湖群体首先聚为一支,然后与由钱塘江群体、太湖群体、衢州群体和洪湖群体聚成的分支聚在一起,而后与洞庭湖群体聚在一起,最外侧一支为鄱阳湖群体。分子方差分析(AMOVA)得出群体间的遗传分化指数(Fst)为0.2081(P<0.001),说明我国褶纹冠蚌不同群体间存在一定的遗传分化。

The genetic diversity of Cristaria plicata were conducted by using mitochondria DNA COI gene as molecular marker. 620 bp lengths of homological fragments in 200 individuals from ten stocks captured in the middle and lower Yangtze River were sequenced. The average contents of A ＋ T （60.1% ） were significantly higher than those of G ＋ C （39.9%）. The sequences contained 105 polymorphic nucleotide variable sites, accounting for 17% of the total number of bases. The ratio of transition and transversion was 8.7. Fifty eight haplotypes were defined （GenBank accession number： EU698893- EU698950） in this study, in which Hap-5 was the major haplotype, accounting for 41% of the total individual number. The average nucleotide difference and nucleotide diversity index of Poyanghu population were 25.426 and 0.041 O1 respectively, which were the highest. Genetic diversity parameters of Taihu and Quzhou populations were lowest. Based on the genetic distance among populations, Neighbor-Joining （NJ） tree suggested that three populations of Hongzehu were clustered firstly and then clustered with Chaohu population. The second clade comprised Qiantangjiang population, Taihu population, Quanzhou population, as well as Honghu population. The third clade included Dongtinghu population, and finally clustered with Poyanghu population. The fixtion index （ Fst ） calculated by the analysis of molecular variance （AMOVA） reached to 0. 208 1 （ P 〈 0.001 ）, indicating that there were some genetic differentiations in different populations of C. plicata in China.