Genetic connectivity of black drum (Pogonias courbina) stocks in the southwestern Atlantic Ocean

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

“…Most surrounding haplotypes were unique to each sampling site and showed few differences among them (Figure 2). Similar star-like haplotype networks have been observed for other species in different coastal areas: Terapon jarbua, which consists of a panmictic stock from the Socotra Archipelago to the Hadhramout Coast along the wider Gulf of Aden (Lavergne et al, 2014); and Pogonias courbina, which did not display distinct structure along the coast of the southwestern Atlantic Ocean (Machado et al, 2020).…”

“…Studies of population connectivity with mitochondrial markers provide critical information on gene flow and genetic relationships between neighboring populations (Turner et al, 2004;García et al, 2008). Many studies showed that mitochondrial markers are highly effective for revealing marine fish genetic diversity and population connectivity (Lavergne et al, 2014;Gao et al, 2019;Machado et al, 2020). In this study on E. cardinalis, mtDNA sequence analysis of specimens from Beibu Gulf revealed no significant genetic differentiation among sampling sites, with low Φ ST values indicating genetic homogeneity.…”

“…In contrast to freshwater fish, marine fish are generally expected to show relatively low genetic differentiation across their distribution. It is mainly attributed to genetic exchange being maintained by adult mobility throughout Beibu Gulf during reproduction, and through the passive dispersal of eggs and larvae due to the lack of noticeable physical barriers in pelagic oceans (Grant and Bowen, 1998;Hellberg, 2009;Machado et al, 2020). The dominant widespread haplotype H1 was found in all 11 sampling sites, which also indicated high dispersal potential of E. cardinalis at planktonic egg, larval, or adult stages in Beibu Gulf.…”

“…The effectiveness of marine protected areas depends on both their ability to self-recruit (reproductive potential) and the spillover of adults and export of larvae to nearby fished areas (Harrison et al, 2012;Le Port et al, 2017). Over the last 30 years, population genetic studies have become an essential tool for stock management and conservation of coral reef, estuarine, and coastal populations because population genetic studies are useful for estimating genetic diversity and the ability to survive anthropogenic activities such as overfishing, habitat degradation, eutrophication, invasive species, and pollution (Ryman et al, 1995;Ruzzante et al, 1998;Gill and Kemp, 2002;Gaither et al, 2010;Machado et al, 2020). Mitochondrial DNA markers (mtDNA) are widely employed to detect population structure in marine species because they have large number of copies, high mutation rates, generally maternal inheritance, and almost nonexistent recombination.…”

“…The primary advantages of mtDNA are the inheritance pattern and nonexistent recombination: speciation events over multiple generations can be traced through maternal cloning, and male dispersal does not homogenize the population (Prugnolle and de Meeus, 2002). These factors make mtDNA markers particularly suitable indicators of the genetic structure of marine populations with high gene flows, such as zooplankton and migratory fishes (Wang et al, 2013;Xu et al, 2019;Machado et al, 2020).…”