基于线粒体D-loop区探讨我国养殖大口黑鲈的分类地位和遗传变异

Approach on the taxonomic status and genetic variation of largemouth bass(Micropterus salmoides) cultured in China based on mitochondrial D-loop gene

对大口黑鲈国内养殖种群(G)和北方亚种(N)、佛罗里达亚种(F)两个野生种群共23个个体的线粒体DNA D-loop区序列进行分析,探讨国内养殖大口黑鲈(Micropterus salmoides)的分类地位和遗传变异。D-loop区序列分析结果表明,共检测到73个变异位点,总变异率为9.0%。三群体间没有共享单倍型,群体G的5个个体含2种单倍型,群体N的11个个体含9种单倍型,群体F中每个个体均为一种单倍型。对三个群体间的遗传距离分析表明,养殖群体与北方亚种野生群体的遗传距离为0.009,与佛罗里达亚种野生群体的遗传距离为0.053,表明国内养殖的大口黑鲈在分类上属于北方亚种,分子系统进化树的进一步分析结果与其一致。群体N、F和G的核苷酸多样性指数(π)依次为0.008 2,0.013和0.000 5,单倍型多样性指数(h)分别为0.946,1.000和0.400,显示出养殖大口黑鲈群体的遗传多样性相比国外野生群体有明显下降,有必要开展大口黑鲈的遗传改良研究,提高其种质质量。

Using nucleotide sequences from control region （D-loop） of mitochondrial, the taxonomic status and genetic variation of largemouth bass cultured population in China have been approached. The results from sequence analysis of 23 samples including largemouth bass cultured population （G） in China and two wild populations for northern subspecies （N） and Florida subspecies （F） both from America revealed that there were 73 variable sites （9%） among 810 bp. Among three populations,there was no shared haplotype to be detected, and the number of haplotype in population G, N and F was 2, 9 and 7, respectively. The genetic distances of intrapopulation of three populations have been analyzed. The genetic distance between population G and N was very low （0.009）, but it exhibited significant genetic difference （0. 053 ） between population G and F. According to the fact mentioned above, it came to the conclusion that largemouth bass cultured in China should attribute to the northern subspecies, corresponded with molecular phylogenetic tree analysis. Estimation of the nucleotide diversity of population N, F and G was 0.008 2, 0.013 and 0.000 5, respectively, and the haplotype diversity was 0. 946, 1.00 0 and 0.400, respectively. These data showed that the genetic diversity of largemouth bass cultured population decreased significantly as compared with that of wild population. It was necessary to carry out the genetic improvement to improve the quality of largemouth bass germplasm.