Genetic diversity and population structure of small yellow croaker (Larimichthys polyactis) in the Yellow and East China seas based on microsatellites

Small yellow croaker (Larimichthys polyactis), a member of family Sciaenidae, is mainly distributed in the northwestern Pacific Ocean. To assess the genetic diversity and population structure of this species across its range, we genotyped 150 L. polyactis individuals sampled in five locations along the coast of the Yellow and East China seas using 20 polymorphic microsatellites. A total of 499 alleles were detected at 20 loci across all individuals, and a relatively high level of genetic diversity was observed, with observed heterozygosity (Ho), expected heterozygosity (He) and polymorphic information content (PIC) ranging from 0.233 to 1.000, from 0.438 to 0.955, and from 0.367 to 0.953 per locus-location combination, respectively. Analysis of molecular variance (AMOVA) (FST = 0.00915, P < 0.001), pairwise FST, and corrected average pairwise differences indicated that there was extremely low, but statistically significant genetic differentiation among the studied populations. However, Bayesian assignment analysis revealed a high number of immigrants among populations and no obvious genetic differentiation. The Wilcoxon signed-rank test and mode-shift indicator of allele frequency distribution support the inferrence that L. polyactis had not experienced a recent genetic bottleneck. Overall, the results suggest that, despite low genetic differentiation in this species, the small yellow croaker forms a single panmictic population with high genetic variation and gene flow in the studied area. This study will provide useful information for conservation and sustainable exploitation of this important aquatic living resource