Population panmixia and the Pleistocene demographic expansion of spotty belly greenling Hexagrammos agrammus in the East Sea and Northwest Pacific

Abstract

The population genetic structure and historical demography of spotty belly greenling, Hexagrammos agrammus, which has limited distribution in the Northwest Pacific, was assessed with partial sequences of the mitochondrial DNA (mtDNA) cytochrome b and the control region (D-loop). A total of 103 individuals were collected from four sites located at the Korea Strait (Southern coast of Korea) and the East coast of Korea and two places in the Pacific coast of Japan. For all the populations, nucleotide diversities were low (0.006-0.009) while the haplotype diversities were as high as 0.92 to 0.97, indicating that the fish has undergone a recent population expansion after experiencing bottleneck. Star-shaped patterns of haplotype networks as well as the significant negative values of Tajima's D and Fu's F (S) corroborate the recent population expansion. Mismatch distribution analysis reveals that the demographic expansion of the species started during the 2(nd) half of the Middle Pleistocene Series approximately 141,000-406,000 years ago. Hierarchical analysis of molecular variance (AMOVA), the pairwise population statistics (F (ST)), and the exact test of haplotype differentiation demonstrate no significant genetic differentiation among populations investigated, suggesting that spotty belly greenling is panmictic in the East Sea and the Pacific coast of Japan.