Genetic Diversity and Population Genetic Structure of Korean Black Scraper Thamnaconus modestus in Korea and Japan Based on the mtDNA Marker

Abstract

Thamnaconus modestus is a commercially important species that is widely distributed in the Northwest Pacific region. To investigate the genetic diversity, demographic history, and population structure, 84 individuals were collected from two locations in Korea (Geomundo and Jumunjin) and one location in Japan (Wakasa Bay). Analysis of the mitochondrial DNA control region sequence of 373 base pairs from the 84 individuals revealed 39 haplotypes with 50 polymorphic sites. The haplotype diversity and nucleotide diversity of different populations ranged from 0.973 (0.018) to 0.981 (0.013) and from 0.020 (0.011) to 0.021 (0.011), respectively. Phylogenetic analysis revealed three distinct clades of which two were large (clade 1 and clade 2) and one was small clade (clade 3). However, there was no significant geographical clustering of the haplotypes according to the sampling locality. Demographic analysis suggested that both clades experienced Late Pleistocene population expansion. The pairwise F-ST and AMOVA analysis were insignificant among the populations investigated. This indicated high gene flow among the populations of Korea and Japan. The dispersal capacity of the larvae and juveniles by ocean currents and migration of adult individuals could explain the genetic homogeneity. Insufficient time to accumulate genetic variation might be another reason for the lack of genetic structure.