Significant population genetic structure detected in the small yellow croaker Larimichthys polyactis inferred from mitochondrial control region

The population genetic structure of the small yellow croaker (Larimichthys polyactis) between China and Korea was further estimated by broad-scale sampling locations (Gulf of Bohai, Yellow Sea including Korea). One hundred and seventeen individuals from eight localities from coastal waters of China and Korea were analyzed based on mtDNA control region sequences (50 mtDNA CR). A total of 97 polymorphic sites were checked, which defined 136 haplotypes. A pattern with high levels of haplotype diversity (h = 0.994 +/- 0.002) and nucleotide diversity (pi = 0.020 +/- 0.010) was detected in the examined range, and the genetic diversity of Korea populations was higher than that of China populations. Population genetic structure analyses (MDS, AMOVA, Fst, Barrier) showed that significant genetic differentiation existed between China and Korea populations. The migration analysis indicated asymmetry migration also existed among populations, which was consistent with the result of population genetic structure. Using a variety of phylogenetic methods, coalescent reasoning, and molecular dating interpreted in conjunction with paleoclimateic and physiographic evidence, we inferred that the genetic make-up of extant populations of L. polyactis was shaped by Pleistocene environmental impacts on the historical demography of this species. Coalescent analyses (Neutrality tests, Mismatch distribution analysis, Bayesian skyline analyses) showed that the species along coastline of China and Korea has experienced population expansions originated in its most recent history at about 32-196 kya and 166-662 kya before present, respectively.