The impact of Yangtze River discharge on the genetic structure of a population of the rock bream,Oplegnathus fasciatus

Abstract

As a rocky reef species, Oplegnathus fasciatus displays significant geographic differences that may be congruent with patterns of molecular variation. We used 10 polymorphism microsatellite loci to characterize the genetic structure and test the impact of ocean currents and the Yangtze River on the population genetic connectivity of the rock bream, O. fasciatus, sampled from Jiaonan (JN), Zhoushan (ZS) and Taiwan (TW). The average number of alleles was 17.78, with a total of 160 alleles, and the average allele value in the East China Sea (ZS = 13.70) was higher than that in the Yellow Sea (JN = 6.70). The individuals at the ZS location showed the highest expected heterozygosity (He = 0.86), Nei's genetic diversity (H = 0.84) and Shannon genetic diversity (I = 2.21). Genetic bottleneck tests showed that individuals had experienced a recent bottleneck effect in the JN location. AMOVA analysis showed that 12.19% of genetic variation existed among populations, indicating significant population genetic differentiation in the species. The values of the population pairwise differentiation index (F st and Φ pt ) ranged from 0.01 to 0.29. The UPGMA tree showed two diverged genealogical branches corresponding to sampling localities (Clade A = JN, Clade B = ZS and TW) in the species. The AMOVA and STRUCTURE analyses suggested that O. fasciatus may be composed of two stocks in the examined range, and the freshwater discharge from the Yangtze River might act as a physical barrier to genetic exchange between north and south China stocks of the species. ARTICLE HISTORY

Molecular and Fitness Data Reveal Local Adaptation of Southern and Northern Estuarine Oysters (Crassostrea ariakensis)

“…The Yangtze River estuary is known to be a notable barrier for the distribution of many marine invertebrates with lower gene flow, such as two oyster congeners of C. gigas and C. angulata (Xu, 1997;Li et al, 2017), an interpopulation of limpet (Cellana toreuma) (Dong et al, 2012) and the bivalve Cyclina sinensis (Ni et al, 2012(Ni et al, , 2017. Even marine species exhibiting high gene flow with high mobility or a long-term larval stage showed a distinctive genetic structure between the northern and southern coasts of the Yangtze River (Xu et al, 2009;Xiao et al, 2016). In addition, in line with a previous study (Xiao et al, 2010), oysters inhabiting the Yangtze River estuary were clustered with their northern counterparts.…”

“…In China, the Yangtze (Chang Jiang) River has long been rendered as a marine biogeographic boundary causing distinct ecological gradients, especially for temperature and salinity, and shaping adaptive differentiations in warm-tolerant and coldwater populations or species of coastal animals under spatially varying selection. Ni et al (2017) comprehensively summarized the effects of the Yangtze River as well as its interaction with coastal currents on the genetic diversity of many marine species, such as fishes, crabs, mollusks, etc., Most of the marine species exhibited divergent genetic structures between the northern and southern populations separated by the Yangtze River, while coastal currents facilitate internal gene flows within the northern or southern populations (Xu et al, 2009;Xiao et al, 2016;. These findings highlight the significant role of stochastic geographic isolation following environmental selection in ecological, evolutionary, and taxonomic studies.…”

More than meets the eye: The barrier effect of the Yangtze River outflow

“…Combined with contributions from other rivers, a large delta plain with an area of more than 3 × 10 4 km 2 has developed (Saito, Yang, & Hori, ), and a sedimentary coast of mud substrate has been formed from Lianyungang (34°36′N, 119°13′E) to Shaoxing (30°19′N, 120°46′E) with a straight‐line distance of over 500 km (Zhu, Gao, & Zhu, ) (Figure a). These environmental changes may have drastically influenced phylogeographic patterns of coastal species (with low tolerance to salinity changes or with habitat specificity) and left genetic signatures in contemporary populations (Wang, Tsang, & Dong, ; Xiao, Ma, et al., ).…”

Genome of the estuarine oyster provides insights into climate impact and adaptive plasticity

“…The standing genetic variation of a species is the outcome of its evolutionary history shaped by mutation, selection and genetic drifts ( 4–6 ). Past and on-going climate and geological events may leave signatures of selection or bottleneck in the genome and influence the geographic distribution of genetic variation ( 7–9 ). Many recent studies have revealed the significance of phenotypic plasticity in environmental adaptation ( 10–15 ).…”