Population analysis of Scomberomorus cavalla (Cuvier, 1829) (Perciformes, Scombridae) from the Northern and Northeastern coast of Brazil

Scomberomorus cavalla is a pelagic fish species widely distributed on the Atlantic west coast, and a noticeable decrease in its capture level in the USA and Gulf of Mexico is occurring, compared to the levels reached by the species in the past. Likewise, in some areas of Brazil, there has been indication of over-harvesting. However, there are no molecular studies focusing on the management of such an important item. Thus, in the present study, 380 nucleotide base pairs of the mitochondrial DNA D-Loop region of samples from Macapá, Bragança, and Fortaleza were sequenced. Phylogenetic and population analyses revealed that there is only one panmitic population, and low levels of genetic variability were verified. These results, as well as the noticed over-harvesting of S. cavalla, represent very important data to determine the management of such stock in order to prevent a collapse or the risk of future extinction

Population Structure of Lutjanus purpureus (Lutjanidae - Perciformes) on the Brazilian coast: further existence evidence of a single species of red snapper in the western Atlantic

The present study focus on the mitochondrial control region to investigate phylogeographic patterns and population structure in Lutjanus purpureus, and to evaluate the genetic similarity between L. purpureus and L. campechanus. For the initial analysis, 810 base pairs sequence from control region were obtained from 239 specimens of L. purpureus collected from four localities off the Brazilian coast. The results revealed the presence of a single panmictic population characterized by high values of genetic diversity. The 299 base pairs hypervariable portion were used for the combined analysis of L. purpureus and L. campechanus, being 275 haplotypes identified in the 414 specimens. Phylogenetic tree and haplotype network did not indicate phylogeographic substructuring between the two species, but rather an intense intermingling of individuals. Considering their marked morphological similarity, the molecular data presented here indicate that only one species of red snapper exists in the western Atlantic.<br>Para o presente estudo utilizou-se a região controle mitocondrial para investigar os padrões filogeográficos e a estrutura populacional de Lutjanus purpureus e para avaliar a similaridade genética entre L. purpureus e L. campechanus. Para a análise inicial foram obtidas sequências de 810 pares de bases (pb) da região controle para 239 espécimes de L. purpureus de quatro localidades da costa brasileira. Os resultados mostraram a presença de uma população panmítica caracterizada por altos valores de diversidade genética. Utilizou-se um segmento de 299 pb da porção hipervariável para comparar L. purpureus e L. campechanus. Dos 414 indivíduos analisados foram identificados 275 haplótipos. A árvore filogenética e a rede de haplótipos não mostraram subestruturação filogeográfica entre as duas espécies, com intensa mistura de indivíduos. Considerando a grande similaridade morfológica, os dados moleculares apresentados, aqui indicam que apenas uma única espécie de pargo vermelho existe ao longo do atlântico ocidental