栉孔扇贝、虾夷扇贝及其杂交子代线粒体COI和Cytb基因遗传多样性分析

Genetic diversity analysis of Chlamys farreri, Patinopecten yessoensis, and their offspring based on COI and Cytb sequences

为了解栉孔扇贝(Chlamys farreri)、虾夷扇贝(Patinopecten yessoensis)及其杂交子代(F1)的种群遗传多样性和遗传结构,对3个群体的线粒体COI和Cytb基因的部分序列进行了扩增和分析。经比对分别获得781bp和725bp核苷酸片段,74个样本共检测到47个单倍型;F1群体的单倍型数、单倍型多样性指数、核苷酸多样性及平均核苷酸差异数都是最高的,而双亲的较低;F1和栉孔扇贝间的遗传距离最小,其次为栉孔扇贝和虾夷扇贝群体之间,F1和虾夷扇贝群体之间的遗传距离最大;F1和栉孔扇贝之间的遗传分化系数较小而两者间的基因流比较大,F1和栉孔扇贝与虾夷扇贝之间的遗传分化系数较大而基因流较小,说明栉孔扇贝和虾夷扇贝群体群体很早就发生了遗传分化;采用UPGMA法和简化的中介网络法构建的系统树表明,3个群体的所有个体被分为2个族群,栉孔扇贝和F1交叉聚为一类,虾夷扇贝独自聚为一类,2个分支间没有交叉;使用特异性引物分别对3个群体进行PCR扩增检验,结果栉孔扇贝的特异引物能在杂交子代中扩增,而虾夷扇贝的特异引物不能在子代中扩增出条带,说明栉孔扇贝和虾夷扇贝杂交,其子代的线粒体遗传模式为严格的母系遗传。本研究结果表明杂种优势的形成与线粒体遗传多样性的变化有关。

Mitochondrial DNA cytochrome oxidase subunit I（COI） and cytochrome b（Cytb） gene fragments were amplified and analyzed to examine the genetic diversity and structure of three scallop populations： Chlamys farreri, Patinopecten yessoensis, and their hybrid（F1）. Fragments with 781 bp of the partial COI gene and 725 bp of the partial Cytb gene were obtained after alignment and emendation, and 47 haplotypes were found in the sequences of the 74 samples. The genetic diversity indexes, including the haplotype number, haplotype diversity, nucleotide diversity, and average number of nucleotide differences, showed that the genetic diversity of F1 was greater than that of the parents. The genetic distance between F1 and C. farreri was the nearest and that between F1 and P. yessoensis was the farthest. The level of gene flow between F1 and P. yessoensis was less than the level between F1 and C. farreri, while the population differentiation values between F1 and P. yessoensis was greater than the value between F1 and C. farreri, suggesting that the differentiation between C. farreri and P. yessoensis happened a long time ago. A UPGMA tree and reduced median network of haplotypes led to the same result, with the population of C. farreri and F1 gathered together and the population of P. yessoensis gathered together independently. PCR reamplification revealed that the special primers of C. farreri could be amplified but the P. yessoensis special primers could not be amplified in the F1 population, indicating that the mitochondrial DNA genetic model of F1 represented matrilinear inheritance.