Genetic diversity and structure analyses of largemouth bass (Micropterus salmoides) original and cultured populations based on microsatellite markers.
In order to examine the genetic background of Micropterus salmoides, eleven microsatellite loci were used to study the genetic diversity and structure of the introduced subspecies (California M. salmoides), selected subspecies from Taiwan Province (Taiwan-California M. salmoides) and cultured species (Youlu No. 1) in mainland. The results showed that both the number of alleles and effective alleles was higher in California M. salmoides than in Taiwan-California M. salmoides and Youlu No. 1. The observed heterozygosity and expected heterozygosity at five loci were significantly higher in California population than in Taiwan-California and Youlu No. 1 populations, which were similar. According to the polymorphic information content, eleven loci in the California population were at high polymorphic levels. Six loci and four loci were at highly polymorphic levels for Youlu No. 1 and Taiwan-California populations, respectively. In the genetic equilibrium test, it was found that there were more loci deviating from Hardy-Weinberg equilibrium in Taiwan-California population, and there were three linkage pairs in California population (P < 0.05). For the two-phased model of mutation (TPM), both WILCOXON and sign tests showed that California population was in a status of mutation-drift disequilibrium. For population structure, it was found by analysis of molecular variance (AMOVA) that 15.57% of the genetic variation came from among populations, 25.05% from within populations, and 59.38% from among individuals (P < 0.01). The genetic distance between California population and Youlu No. 1 population was the largest, followed by that between California population and Taiwan-California population. When the K was two, there were significant differences in genetic structures between California population and other two populations. Through individual population identification, California population had the lowest rate of misjudgment, followed by Youlu No. 1 and Taiwan-California populations. When the accuracy was 85.00%, the probabilities of correct discrimination of California, Youlu No. 1 and Taiwan-California populations were 67.70%, 53.30% and 20.00%, respectively. According to the analysis of genetic diversity, genetic distance and equilibrium test, it was found that the original species of California had high polymorphism, and the genetic distance was bigger than that of the other two populations, and there might be genetic bottleneck. It is suggested that the species of M. salmoides introduced from the United States should be expanded and cultivated systematically.