基于线粒体DNA控制区序列的极边扁咽齿鱼群体遗传研究

Comparative Analysis of Genetic Variation between Wild and Cultured Populations of Platypharodon extremus Based on Mitochondrial DNA D-loop Sequence

极边扁咽齿鱼是黄河上游特有的裂腹鱼类,由于人类活动的加剧,使其野生数量急剧下降,近年来通过增殖放流的方式为野生资源量进行补充。为评价增殖放流过程中人工繁育群体对野生群体的种质资源的影响,笔者利用线粒体DNA控制区(D-loop)序列来探究极边扁咽齿鱼野生和养殖的4个群体遗传多样性、遗传分化及遗传结构的差异。研究结果显示,4个群体均表现出了较高的单倍型多样性(0.950±0.011)和较低的核苷酸多样性(0.00987±0.00041),并且野生群体的单倍型数目、单倍型多样性指数、核苷酸多样性指数均高于人工繁育群体。遗传结构分析结果显示,野生群体与人工繁育群体之间已产生了一定的遗传分化。中性检验表明,2个野生群体可能经历过种群扩张事件。研究结果表明,极边扁咽齿鱼人工繁育群体可能受到亲本数量有限、人工选择等影响,遗传多样性略有降低,有必要定期开展增殖放流效果的评估,并采用科学的人工繁育方法,丰富极边扁咽齿鱼种群的遗传多样性。

In this study,the mitochondrial DNA control region(D-loop)gene sequences were analyzed in 21 samples of wild Platypharodon extremus collected from Maqu County in Gansu Province and Maduo in Qinghai Province and 39 samples of F 1 and 38 samples of F 2 cultured P.extremus in Linxia,Gansu Province.The results showed that there were high haplotype diversity(H d=0.950±0.011)and low nucleotide diversity(P i=0.00987±0.00041)in the four populations,with the higher haplotype number(N h),haplotype diversity index(H d)and nucleotide diversity index(P i)in the wild population than those in the cultured population.The analysis of genetic structure showed there was genetic differentiation between the wild population and cultured population.The neutral test revealed that the two wild populations had population expansion events.In conclusion,the cultured populations slightly showed the reduce in genetic diversity due to effect of the limited number of breeding fish and artificial selection.So it is necessary to evaluate the effect of breeding and releasing regularly and use scientific artificial breeding methods to enrich the genetic diversity.