Genetic diversity and genetic differentiation of three genetic-ecological populations ["Pujiang No.1"selected strain F7(PJ), two domesticated populations(HX, GA) as well as four wild populations(LZ, YN, SS,JL)]of blunt snout bream (Megalobrama amblycephala) were analyzed by using combined nucleotide sequences of control region and CO I gene of mitochondrial DNA (mtDNA).The results showed that: (1) Sixty-four haplotypes were defined in analyzed seven populations, in which no haplotype was shared among populations.(2) The haplotype diversity(Hd), number of variable sites, nucleotide diversity(π) and average number of nucleotide differences(K) were 0.857-0.943, 31-40, 0.275％-0.461％ and 4.043-6.800, respectively in four wild populations.The four corresponding parameters were 0.714-0.800, 18-21, 0.122％-0.175％ and 1.800-2.586, respectively in two domesticated populations, which were lower than those in the four wild populations.Likewise, those parameters were 0.843, 23, 0.193％ and 2.843, respectively in genetically selected strain F7, which were lower than those in the four wild populations but higher than those in two domesticated populations.The above four genetic diversity parameters showed the same trend of change among seven populations.(3) For the seven populations studied,average genetic distance between populations ranged from 0.000 6 to 0.003 5.The pairwise FST value between populations ranged from 0.010 9 to 0.133 1.For pairwise FST value between populations, P value of permutation test were significant(P＜0.05) between GA, HX and PJ populations, but no significant P value(P＞0.05) were detected between four wild populations.The results indicated that distinct living environments (natural waters and closed fishponds) and artificial selection( strictly and orderly scientific breeding) had a strong impact on the population genetic structure, making difference in genetic variability and genetic differentiation between different types of genetic-ecological populations.%通过对线粒体DNA控制区和COⅠ基因序列的联合分析,研究了团头鲂(Megalobrama amblycephala)3类遗传生态群体(包含4个野生群体、2个驯养群体、1个选育良种"浦江1号"群体)的遗传多样性和遗传分化情况.结果表明:(1)在所分析的7个群体中,共确定了64种单倍型,群体间无共享单倍型.(2)4个野生群体内线粒体DNA的单倍型多样度(Hd)在0.857～0.943之间,核苷酸变异位点数在31～40之间,核苷酸多样性指数(π)在0.275%～0.461%之间,平均核苷酸差异数(K)的范围为4.043～6.800;2个驯养群体的相应参数变化范围分别为0.714～0.800、18～21、0.122%～0.175%、1.800～2.586,均低于野生群体;选育群体的相应参数分别为0.843、23、0.193%、2.843,低于4个野生群体,但高于2个驯养群体.以上4种多样性参数在7个群体中的变化趋势一致.(3)7个群体之间的平均遗传距离在0.000 6～0.003 5之间,遗传分化指数(FST)在0.010 9～0.133 1之间.4个野生群体间FST值差异不显著(P＞0.05),而2个驯养群体间FST值差异显著(P＜0.05),它们与选育群体间的FST值差异也显著(P＜0.05).以上结果表明,生存环境的殊异(敞开的天然水体,封闭的驯养池塘)和人工选择(严格有序的科学选育)对种群遗传结构影响巨大,导致鱼类不同遗传生态类型群体间产生遗传变异和遗传分化.
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