Mitochondrial DNA evidences reflect an incipient population structure in Atlantic goliath grouper (<em>Epinephelus itajara</em>, Epinephelidae) in Brazil

Abstract

Summary:The Atlantic goliath grouper is a critically endangered species that inhabits estuarine and reef environments and is threatened primarily by fishing activities and habitat destruction. Despite the urgent need for protection, its genetic conservation status remains unknown. The aim of the present study was to evaluate the gene flow among the populations of the species along the coast of Brazil based on the control region of the mitochondrial DNA. The results indicate low haplotype diversity (0.40-0.86) and very low nucleotide diversity (0.1-0.5%). They also show that the genetic diversity of the species varies considerably along the coast and that this finding may be especially important for the identification of priority areas for its conservation. The population analyses indicate a low but significant degree of genetic structuring (Φ ST =0.111), probably due to the occurrence of rare haplotypes at some locations, although the genetic differentiation between sites was not correlated with geographic distance (r=0.0501; p=0.7719), and the shared haplotypes indicate that gene flow occurs among all locations along the Brazilian coast. The results of the pairwise F ST indicate a high degree of genetic differentiation between locations. The incipient population structuring detected in the present study is not related systematically to the geological or physical features of the Brazilian coast. The complex interaction of fluctuations in sea level, marine currents, and the reproductive characteristics of the species hampers the identification of the specific role of each of these processes in the gene flow dynamics of the population units of the Atlantic goliath grouper. The low overall levels of genetic diversity, the pairwise F ST values and the significant population structuring among groups (Φ CT ) identified in the present study all reinforce the critically endangered status of the species and are inconsistent with the presence of a single, panmictic population of groupers on the Brazilian coast. The results of this study suggest that, though it may be incipient, the observed genetic structuring must be taken into account in order to prevent potential problems, such as outbreeding depression, in the management of wild stocks.Keywords: critically endangered species; gene flow; genetic diversity; marine fish; western Atlantic Ocean.Evidencias en el ADN mitocondrial reflejan una incipiente estructuración poblacional en el mero guasa del Atlántico (Epinephelus itajara, Epinephelidae) en Brasil Resumen: El mero guasa del Atlántico está críticamente en peligro, habita en ambientes estuarinos y arrecifes, los cuáles están amenazados principalmente por las actividades de pesca y la destrucción de su hábitat. A pesar de la necesidad urgente de protección, su estado de conservación genética aún es desconocido. El objetivo del presente estudio fue evaluar el flujo génico entre las poblaciones de esta especie a lo largo de la costa de Brasil analizando la variabilidad genética de la región control del ADN mitocondrial....

Population genetic structure of an estuarine and a reef fish species exploited by Brazilian artisanal fishing

“…Along the Brazilian coast, evidence of a genetic pattern related to geographic distribution was not observed in Ocyurus chrysurus (Lutjanidae) (Vasconcellos et al 2008) or Cephalopholis fulva (Epinephelidae) (De Souza et al 2015). Such evidence was also not found in some studies on Epinephelus itajara (Epinephelidae) (SilvaOliveira et al 2008, Damasceno et al 2015. Genetic differentiation in samples from Santa Catarina State in relation to other locations was observed for Epinephelus itajara (Benevides et al 2014).…”

Population genetic structure and demographic history of the spadefish, Chaetodipterus faber (Ephippidae) from Southwestern Atlantic

“…Regarding the mtDNA D-loop, results showed moderate to high haplotype diversity (h) and low nucleotide diversity (π) when compared with other marine fishes (Aboim et al, 2005;Damasceno et al, 2015;Ju et al, 2013;Planes et al, 2001;Stepien et al, 2001;Santos et al, 2006). Furthermore, a significant genetic divergence between Tropical and Subtropical groups of C. faber in SW Atlantic was identified, suggesting a restriction to gene flow.…”

“…These observations highlight the need of studies along the NE Brazilian coast, mainly using SNPs or microsatellite markers to better understand such pattern. The hypothesis of larval retention appears to be one of the main explanations to be evaluated, especially in a species like C. faber, which gather in spawning aggregations and depend on estuarine environments for larval and juvenile development (Barros et al, 2013;Bittencourt, 1990;Ditty et al, 1994;Hayse, 1990;Damasceno et al, 2015). Larval retention by aggregated spawning species may be selectively advantageous to ensure the access of larvae and juveniles to necessary resources (Portnoy et al, 2013).…”

“…Larval retention by aggregated spawning species may be selectively advantageous to ensure the access of larvae and juveniles to necessary resources (Portnoy et al, 2013). Moreover, resident breeding groups may potentialize larval retention resulting in reduced gene flow (Damasceno et al, 2015).…”

Genetic diversity and populational structure of the seahorse Hippocampus reidi (Syngnathidae) in north‐eastern Brazil: A conservationist approach

“…In the region adjacent to the area studied here, other fish species have also exhibited similar population structure. Such is the case of Epinephelus itajara , Holacanthus ciliaris , and Macrodon ancylodon , which were evaluated using mitochondrial and nuclear genes (Affonso & Galetti Jr, ; Damasceno et al, ; Santos, Schneider, & Sampaio, ). Sea currents and environmental conditions may explain these findings (Boehm et al, ).…”