Evidencias en el ADN mitocondrial reflejan una incipiente estructuración poblacional en el mero guasa del Atlántico (Epinephelus itajara, Epinephelidae) en Brasil

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 (ΦST =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 FST 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 FST values and the significant population structuring among groups (ΦCT) 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.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. Los resultados indican baja diversidad haplotípica (0.40-0.86), y una muy baja diversidad nucleotídica (0.1-0.5%). Además se observa que la diversidad genética de la especie varía considerablemente a lo largo de la costa y este resultado puede ser especialmente relevante para la identificación de áreas prioritarias de conservación. Los análisis poblacionales indican un bajo, pero significativo grado de estructuración genética (ΦST =0.111), lo cual es probablemente debido a la ocurrencia de haplótipos raros en algunas localidades, aunque la diferenciación genética entre sitios no está correlacionada con la distancia geográfica (r=0.0501; p=0.7719), y los haplotipos compartidos indican que el flujo génico ocurre entre todas las localidades a lo largo de la costa brasileña. Los resultados de la distancia dos a dos indican un FST de alto grado de diferenciación genética entre las localidades. La incipiente estructuración poblacional detectada en este estudio no está relacionada sistemáticamente con las características biogeográficas de la costa brasileña. La compleja interacción de las fluctuaciones en el nivel del mar, las corrientes marinas, y las características reproductivas de la especie dificultan la identificación del rol específico de cada uno de estos procesos en la dinámica del flujo genético de las diferentes unidades poblacionales del mero guasa del Atlántico. Los bajos niveles generales de la diversidad genética, los valores de FST dos a dos, y la significante estructuración poblacional entre los grupos (ΦCT) identificada en el presente estudio, todo refuerza el estado de peligro crítico de la especie y son inconsistentes con la existencia de una simple, población panmíctica de meros guasa de la costa brasileña. Los resultados de este estudio sugieren que, a pesar de que puede ser incipiente, la estructuración genética observada debe ser tenida en cuenta con el fin de evitar problemas potenciales, tales como la depresión exogámica, cuando se maneja poblaciones silvestres

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

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 (ΦST =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 FST 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 FST values and the significant population structuring among groups (ΦCT) 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

Phylogeography of <i>Hypomasticus copelandii</i> (Teleostei, Anostomidae) Reveals Distinct Genetic Lineages along Atlantic Coastal Drainages of Eastern Brazil

Hypomasticus copelandii is a Neotropical freshwater fish widely distributed across coastal drainages of southeastern Brazil, a highly impacted region of South America. The interspecific phylogenetic relationships within the genus and the taxonomic status of the species remain uncertain. Using two mitochondrial and one nuclear locus, we performed a phylogenetic, species delimitation, and time-calibrated analyses to test the hypothesis that H. copelandii is a species complex currently delimited by different Atlantic coastal systems. Results indicate that H. copelandii presents two well-delimited genetic lineages: one in the northern drainages of the Jucuruçu, Mucuri and Doce rivers, and the other in the southern region represented by the Paraíba do Sul River Basin. The time-calibrated phylogeny indicated a split between the two genetic lineages at around 2.8 million years ago (Ma), which might be related to headwater capture events during the Plio-Pleistocene. The discovery of a distinct genetic lineage for H. copelandii suggests distinct management plans for the northern and southern drainages. Such hidden diversity within the H. copelandii provides useful information for taxonomy and conservation across a severely impacted region of Brazil

Molecular identification of Atlantic goliath grouper Epinephelus itajara (Lichtenstein, 1822) (Perciformes: Epinephelidae) and related commercial species applying multiplex PCR

ABSTRACT The Atlantic goliath grouper, Epinephelus itajara , is a critically endangered species, threatened by illegal fishing and the destruction of its habitats. A number of other closely related grouper species found in the western Atlantic are also fished intensively. While some countries apply rigorous legislation, illegal harvesting followed by the falsification of fish products, which impedes the correct identification of the species, is a common practice, allowing the catch to be marketed as a different grouper species. In this case, molecular techniques represent an important tool for the monitoring and regulation of fishery practices, and are essential for the forensic identification of a number of different species. In the present study, species-specific primers were developed for the Cytochrome Oxidase subunit I gene, which were applied in a multiplex PCR for the simultaneous identification of nine different species of Epinephelidae: Epinephelus itajara , E. quinquefasciatus , E. morio , Hyporthodus flavolimbatus , H. niveatus , Mycteroperca acutirostris , M. bonaci , M. marginata , and M. microlepis . Multiplex PCR is a rapid, reliable and cost-effective procedure for the identification of commercially-valuable endangered fish species, and may represent a valuable tool for the regulation and sustainable management of fishery resources