Analysis of Population Genetic Diversity of CynoglossusSemilaevis in Three Groups from Northern China Sea

Abstract

Taking the Cultured and Wild Populations of Cynoglossussemilaevis in Tianjin Coast and cultured Populations in Haiyang as study objects, there were 32746 SNP locis screened by 2b-RAD sequencing. The genetic relationship, genetic structure, genetic diversity in these three groups were also analyzed by SNP markers. The genetic variation within populations (Fis), the genetic variation between groups (Fst), and total variation (Fit) in each SNP locus in these three groups were estimated, which shown that Fstvalue was ranged from 0.0731∼0.1635. The genetic differentiation between Tianjin culture population and Tianjin wild population is the smallest, and the genetic differentiation between Tianjin and Haiyang culture populations, Tianjin wild population and Haiyang culture population is great. The results of selective sweep showed that the polymorphism of wild population was highest in Tianjin, followed by Tianjin culture population, and lowest in Haiyang breeding population. The polymorphism information content (PIC) statistics of Haiyang, Tianjin wild and Tianjin cultured populations respectively in each SNP site shown that Tianjin wild was up to 0.220, followed by Haiyang cultured and Tianjin breeding, the lowest is 0.175. The differentiation between Tianjin wild and Tianjin culture populations is not significant. Principal component analysis was carried out by using software GCTA, and PCA showed that the contribution rates of the first two principal components PC1 and PC2 were 16.25% and 9.54%, respectively, and the cumulative contribution was 25.79%. Two dimensional clustering results show that a small part of the region in Tianjin wild population had a small intervals with that of Tianjin cultured population, but the two principal components generally can be clearly divided into two categories, and these two populations had a clear boundaries with haiyang cultured one. Based on the above SNP locus diversity, polymorphism information content, genetic diversity comparison, the genetic diversity of Tianjin wild population is higher than Haiyang farming groups, but not significant difference between wild and cultured populations in tianjin revealed that Tianjin populations may have a certain extent mixture, which means the possibility of population mixture between wild and culture individuals may exist.