Threadfin Porgy (Evynnis Cardinalis) Haplotype Pattern and Genetic Structure in Beibu Gulf, South China Sea

Lei Xu,Xuehui Wang,Yafang Li,Jiajia Ning,Delian Huang,Lianggen Wang,Feiyan Du,Shuangshuang Liu

doi:10.3389/fenvs.2021.726533

Abstract

Threadfin porgy (Evynnis cardinalis) is one of the important commercial fishing targets of bottom trawl fishery in the northern South China Sea. It is mainly threatened by overexploitation and listed as endangered species in the IUCN Red List. To investigate the demographic history and genetic structure of E. cardinalis population, partial sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene were obtained from 162 individuals collected from Beibu Gulf, South China Sea. In total, 44 different haplotypes were identified, and the dominant haplotype was found in all sampling sites. Across the dataset, nucleotide diversity was low, whereas haplotype diversity was high. Low pairwise comparisons of ΦST and high gene flow among sampling sites revealed a genetically homogeneous population structure in Beibu Gulf, indicating a single panmictic stock of E. cardinalis in this area. The star-like haplotype network, unimodal mismatch distribution, and significantly negative Tajima’s D and Fu’s Fs values indicated recent population demographic expansion of E. cardinalis. The mismatch distribution and Bayesian skyline plot results indicated that E. cardinalis from Beibu Gulf might have experienced colonization and demographic expansion due to sea level fluctuations during the late Pleistocene.

Highlights

Marine fish are generally deemed to have high dispersal potential because of their high moving capability at both larval and adult stages, and the absence of obvious physical barriers to dispersal (Caley et al, 1996; Hellberg, 2009)
The objective of this study was to provide a population genetic analysis using a portion of the mitochondrial cytochrome c oxidase subunit I (COI) gene to assess the population genetic diversity pattern and historical demography, and estimate E. cardinalis expansion time in Beibu Gulf
A homogeneous population structure with low genetic diversity and star-like haplotype pattern was revealed for E. cardinalis in Beibu Gulf of the northern South China Sea

Summary

Introduction

Marine fish are generally deemed to have high dispersal potential because of their high moving capability at both larval and adult stages, and the absence of obvious physical barriers to dispersal (Caley et al, 1996; Hellberg, 2009). A species with the higher dispersal capability, the lower the genetic structure between populations. Understanding the genetic diversity of commercially important species is critical to implement protection policies and management regulations (Araki and Schmid, 2010). Genetic diversity (both within and between populations) greatly influences the adaptive potential of species to environmental changes, and determines their long-term resilience to ecological disturbances (Pauls et al, 2013). Knowledge of genetic structure is useful for understanding the migration routes, areas, and seasons of fish spawning. Such information can help fisheries managers define the spatiotemporal scales over which they can implement effective

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