Genetic Structure and Diversity of the Yellowbelly Threadfin Bream Nemipterus bathybius in the Northern South China Sea

Mu-Rong Yi,Bo Feng,Yun-Rong Yan,Jin-Xi Wang,Hung-Du Lin,Kui-Ching Hsu

doi:10.3390/d13070324

Abstract

The genetic structure and demography of the yellowbelly threadfin bream, Nemipterus bathybius, in the northern South China Sea were examined using the mitochondrial DNA cytochrome b gene (1141 bp). High levels of haplotype and nucleotide diversities (0.98 and 5.26 × 10−3, respectively) showed that all populations exhibited a high level of genetic diversity. Analysis of molecular variance (AMOVA), FST statistics, and haplotype networks suggested the absence of significant genetic differentiation along the coast of the northern South China Sea. Although the results suggested that the lack of differentiation within the population structure of N. bathybius was shaped by ocean currents, our results also showed that the Qiongzhou Strait limited their migration between Beibu Gulf and the northern South China Sea. Neutrality tests and mismatch distributions indicated population expansion, but the Bayesian skyline plots and approximate Bayesian computation approaches suggested that the population sizes recently contracted. The diversification of multiple stocks, which were induced by two ocean current systems, contributed to these discordant results. Although these analyses of demographic history revealed no evidence for recent population bottlenecks, the population demography needs to be evaluated further.

Highlights

China is adjacent to the northwest Pacific Ocean
Kobayashi [20] found a clear intra-island population genetic structure of the sand bubbler crab Scopimera ryukyuensis within the Ryukyu Islands, e.g., at only 20 km. These results suggest that microgeographic genetic structure might exist among some marine species
Excluding the pairwise FST between population SY and populations ST, ZH, and YJ, the values of the pairwise FST were zero (Table 2). These results indicated a lack of genetic differentiation among populations

Summary

Introduction

China is adjacent to the northwest Pacific Ocean. The length of the coastline of mainland China, from the mouth of the Yalu River on the China–Korea border in the north to the mouth of the Beilun River on the China–Vietnam border in the south, is more than 18,000 km (km). Many phylogeographic studies conducted along the coastline of China have proposed that (1) the sea-level fluctuations of marginal seas were greatly impacted by Pliocene and Pleistocene glacial cycles [1,2,3], (2) the oceanographic current systems shape the migrations of marine species [4,5,6,7], and (3) the diluted water of the Yangtze River shapes coastal species differentiation by creating a phylogeographic break [5,8,9]. The macrogeographic population genetic structure among marine species in the Chinese seas has been intensively studied [9,10,11,12,13,14]. Many studies have found that no significant genetic differentiation exists among populations of marine species along the

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Conclusion