长江下游3省湖北钉螺不同地理种群的群体遗传结构研究

Population genetic study of Oncomelania hupensis from three provinces in lower reaches of Yangtze River

目的对长江下游江西、安徽和江苏3省湖北钉螺的不同地理种群进行群体遗传结构分析,以探讨rDNA ITS分子标记在钉螺扩散路径监测中的应用价值。方法采集3省9个种群的钉螺样本,提取基因组DNA,PCR特异性扩增rD NA ITS基因并克隆测序,统计分析群体间的遗传分化系数（Fst）、遗传距离和种群遗传多样性等参数,利用单倍型构建家系网络图。结果9个种群共获得有效序列93条,检测到78个单倍型,平均单倍型多样性、核苷酸多样性分别为0.988和0.012 88,表明钉螺种群的遗传多样性水平较高;其遗传变异主要来自群体内,种群间遗传距离为0.001 6-0.002 3,显示钉螺种群间遗传分化程度较高;家系网络图显示所有单倍型虽可形成3个主要的家系分支,但各地理种群在家系网络图中无明显分化。结论长江下游江西、安徽和江苏3省沿长江分布的湖北钉螺群体遗传多样性主要存在个体间,群体间未形成明显的遗传分化。rDNA ITS分子标记在钉螺扩散路径监测中的应用价值值得进一步探讨。

Objective To analyze the population genetic structure and genetic diversity of Oncomelania hupensis population from Jiangxi,Anhui and Jiangsu provinces along the lower reaches of the Yangzte River in order to explore the application values of rDNA-ITS molecular markers in the surveillance of snail dispersal. Methods The samples about 9 species of O. hupensis snails were collected separately from Jiangxi,Anhui and Jiangsu provinces,and their genomes were extracted,then the partial gene of rDNA-ITS was amplified,cloned and sequenced. Next,the population genetic diversity parameters,including Fixation index（F st）,genetic distance,and genetic variation were calculated. By using the neighbor-joining method,the family map was constructed based on the haplotype. Results A total of 78 haplotypes among 93 sequences were acquired from 9 populations. The average haplotype diversity and nucleotide diversity of 9 populations were 0.988 and 0.012 88,respectively,which showed that the genetic diversity level of O. hupensis snail population was high. The variation was found mainly among the samples,the genetic distances between populations were ranged from 0.001 6 to 0.002 3,which showed a higher degree of genetic differentiation among snail populations. The family map showed that all the haploid types could be divided into three major branches. Conclusions The genetic diversity of O. hupensis population in Jiangxi,Anhui and Jiangsu provinces along the lower reaches of the Yangtze River mainly exists among individuals,and there are no obvious genetic differences among populations. The application of rDNA-ITS molecular markers in surveillance of snail dispersal is worth further discussing.