北盘江光唇裂腹鱼种群基因组DNA遗传多样性的AFLP分析

Genetic diversity of genome DNA in Schizothorax lissolabiatus population from the Beipan River based on AFLP Analysis

为了解珠江水系北盘江光唇裂腹鱼(Schizothorax lissolabiatus)种群遗传多样性的现状,采用8个引物组合对其30尾个体进行了全基因组DNA扩增片段长度多态性AFLP分析。每个引物组合扩增片段数在8~73之间,扩增片段长度为69~500 bp,基因型数为28~30。8个引物组合共计检测出扩增位点975个,平均每个引物组合扩增出121.88个位点;其中多态性位点897个,多态位点比例为92.00%。观测等位基因数(N_(a))、有效等位基因数(N_(e))、Nei遗传多样性指数(H)、Shannon信息指数(I)平均值分别为1.912 3、1.369 0、0.227 1和0.357 5。个体间遗传距离为0.214 7~0.410 9,平均为0.304 0。基于个体间遗传距离构建的UPGMA和NJ系统树具有相似的拓扑结构,均显示30尾光唇裂腹鱼聚为两支,可能分别来源于两个亚群体。北盘江光唇裂腹鱼种群遗传多样性丰富,但由于受水电站建坝、水质污染、过度捕捞等因素的影响,该种群的分布区已缩小,种群数量减少,种群遗传变异离散程度较低并存在着等位基因丢失的现象,应采取措施恢复北盘江光唇裂腹鱼的种群数量,保护其遗传多样性。

Schizothorax lissolabiatus,which belongs to Cypriniformes,Cyprinidae,Schizothoracinae and Schizothorax,is a wild fish species with high economic value distributed in the Yuanjiang River,the Lancang River,the Nujiang River,and the Nanpan River and the Beipan River in the Pearl River system in China.The habitat environment of the rivers for the species had been destroyed to some extent in recent dozens of years because of the influences of human activity.The genetic diversity of Schizothorax lissolabiatus population from the Beipan River in the Pearl River system was studied based on the DNA inspection in the whole genome of 30 individuals of the species in the river by the method of AFLP with 8 primer pairs in this research.A total of 8-73 fragments comprising 69-500 bp respectively were amplified by each of the 8 primer pairs.The amplified fragments of the 8 primer pairs represented 975 loci with an average of 121.88 loci from each primer pair,including 897 polymorphic loci,accounting for 92.00%of the total.The number of genotypes ranged from 28 to 30.The values of the observed alleles(N_(a)),the effective alleles(N_(e)),the Nei’s gene diversity index(H)and the Shannon information index(I)in the population averaged 1.9123,1.3690,0.2271 and 0.3575,respectively.The genetic distance between the 30 individuals varied from 0.2147 to 0.4109,with an average of 0.3040.The unweighted pair group method with arithmetic mean(UPGMA)and neighbor-joining(NJ)phylogenetic trees of the 30 individuals had the similar topological structure according to the genetic distance,which contained 2 branches that probably originated from two different subpopulations respectively.It was speculated that the uplift of the Qinghai-Tibet Plateau caused the ancestral populations of S.lissolabiatus to be distributed in different rivers,the long-term independent evolution and lack of gene exchange between each other had led to the genetic differentiation of the existing S.lissolabiatus populations.This research showed that the genetic diversity of S.lissolabiatus population in the Beipan River was rich.However,the population had a narrower distribution area and smaller size than before and had a low dispersion degree of genetic variation with the loss of allels due to the adverse factors such as hydropower station dams,water pollution and overfishing in the Beipan River,and therefore it is urgent to take effective measures to restore the size of S.lissolabiatus population and protect its genetic diversity in the river.