Population genetic structure of Thryssa kammalensis in the Chinese Seas inferred from control region sequences

Abstract

Thryssa kammalensis (Bleeker, 1849) is a common pelagic species in the Chinese Seas and plays an important role in marine ecosystems. In the present study, 196 individuals of T. kammalensis were collected from nine localities along the Chinese coastal waters. The partial control region sequences of them were sequenced for analysis. Variable numbers of tandem repeats (VNTRs) were common in the control regions of all individuals, which led to variation in sequence length, ranging from 772 to 924 bp. All the populations exhibited high haplotype diversity (0.946–1.000) and low nucleotide diversity (0.015–0.031). Two distinct lineages were identified based on the neighbor-joining (NJ) tree, Bayesian inference (BI) trees, and minimum spanning tree (MST). However, the relative frequency of individuals occupying the two major lineages did not differ significantly among sampling locations. In addition, both molecular variance analysis (AMOVA) and pairwise FST analysis strongly supported little genetic differentiation among populations, revealing no significant genetic structure for T. kammalensis. Neutrality tests and analysis of mismatch distribution suggested that recent population expansion occurred in the two lineages. The climatic changes during Pleistocene periods and dispersal strategy leading to the continual gene flow might have played an important role in the geographical pattern of T. kammalensis.