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

Abstract

<italic>Schizothorax lissolabiatus</italic>, which belongs to Cypriniformes,Cyprinidae,Schizothoracinae and <italic>Schizothorax</italic>, 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 <italic>Schizothorax lissolabiatus</italic> 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 (<italic>N</italic>_a), the effective alleles (<italic>N</italic>_e), the Nei’s gene diversity index (<italic>H</italic>) and the Shannon information index (<italic>I</italic>) in the population averaged 1.912 3, 1.369 0, 0.227 1 and 0.357 5, respectively. The genetic distance between the 30 individuals varied from 0.214 7 to 0.410 9, with an average of 0.304 0. 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 <italic>S</italic>. <italic>lissolabiatus</italic> 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 <italic>S</italic>. <italic>lissolabiatus</italic> populations. This research showed that the genetic diversity of <italic>S</italic>. <italic>lissolabiatus</italic> 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 <italic>S</italic>.<italic>lissolabiatus</italic> population and protect its genetic diversity in the river.