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The genus Octopus occurs in tropical and temperate oceanic waters throughout the world, and currently includes 112 species, although the phylogenetic relationships among the different taxa are still poorly understood. The cosmopolitan Octopus vulgaris is one of the most widely analyzed cephalopods in genetic studies, primarily because of its ample range and the problems associated with the morphological identification of specimens, which indicate the possible existence of a species complex with a worldwide distribution. Two large-bodied octopus species—O. vulgaris and Octopus insularis—are found in the western South Atlantic. The limits of the geographical range of the O. insularis are still unclear. The current study is based on a phylogeographic analysis of the 2 species in the South Atlantic, with the objective of confirming their monophyletic status and the limits of their geographical distribution in this region. The analyses were based on the mitochondrial genes 16S rDNA and Cytochrome Oxidase subunit I (COI). The topologies generated for both genes confirmed the monophyletic status of the 2 species. In the case of O. vulgaris, it was possible to confirm the monophyletic status of the specimens from this region relative to those of other areas around the world, although 3 distinct haplogroups were clearly differentiated, corresponding to the Americas, Europe and Africa, and Asia. The differentiation among these 3 groups may be determined by the limitations of the dispersal of paralarvae among continents. Further studies are needed to confirm the possible occurrence of distinct groups in the western South Atlantic, as well as the influence of oceanic currents on the phylogeographical distribution of O. vulgaris on the Brazilian coast.

Octopus vulgaris is a cephalopod species in several oceans and commonly caught by artisanal and industrial fisheries. In Brazil, O. vulgaris populations are mainly distributed along the southern coast and have been subjected to intensive fishing during recent years. Despite the importance of this marine resource, no genetic study has been carried out to examine genetic differences among populations along the coast of Brazil. In this study, 343 individuals collected by commercial vessels were genotyped at six microsatellite loci to investigate the genetic differences in O. vulgaris populations along the southern coast of Brazil. Genetic structure and levels of differentiation among sampling sites were estimated via a genotype assignment test and F-statistics. Our results indicate that the O. vulgaris stock consists of four genetic populations with an overall significant analogous F ST (Φ CT = 0.10710, P

Growth performance of two Oreochromis niloticus strains, Chitralada and Red-Stirling, their reciprocal crossbred and the Israeli tetra-hybrid ND-56 were assessed in net cages under on-farming conditions. Throughout 268 days of grow-out, the strains were weighed monthly and mortality, feed consumption and water quality were recorded. Ten rigid net cages (1.5 x 1.5 x 1.7 m) immersed in a 10 ha reservoir were linearly arranged near the reservoir outlet following a completely randomized design with two replicates for each treatment (strain). Each cage was stocked with 459 fish (120 fish m(-3)) and fed twice daily to apparent satiation with a commercial tilapia diet following the recommended feeding program. The final mean weights were higher for Chitralada (557.20 g) and the reciprocal crossbreds (522.95, 496.40 g) than those of Red-Stirling (421.90 g). All treatments outperformed the ND-56 tetra hybrid. Daily growth showed statistical differences between Chitralada (2.04 g) and Red-Stirling (1.52 g) but they were statistically the same when compared with the reciprocal crossbreds (1.90, 1.80 g). The relative growth ratios showed the same trend observed in the results for daily growth. The mean survival rate was 98%. The overall growth rate showed that crossbred performed as well as the parental lines. All crossbred progeny presented red colouration with variable pattern of black marks corroborating the dominant inheritance of the red trait in Red-Stirling strain.

A diversidade da seqüência do DNA de oito populações de Octopus cf. vulgaris da costa brasileira e de uma população de Octopus vulgaris proveniente de Portugal foi investigada pelo uso do gene Citocromo oxidase subunidade I (COI) do DNA mitocondrial. Aproximadamente 600 pb do gene COImt foram amplificados por meio dos primers LCO1490 e HCO2198, purificados e seqüenciados. As seqüências foram alinhadas pelo método Clustal W. A árvore filogenética gerada pelo alinhamento das seqüências do COImt revelou dois conjuntos principais, formando clados monofiléticos sustentados por bootstraps superiores a 93%. Um clado contendo os indivíduos provenientes das regiões Sudeste e Sul, similares aos haplótipos de Portugal, que são classificados como Octopus vulgaris, e outro conjunto formado pelos indivíduos coletados em várias localidades das regiões Norte e Nordeste. O nível de diferenciação genética encontrado sugere a presença de duas espécies de Octopus. Quanto à estruturação populacional, os resultados encontrados pelo uso do DNA nuclear e do DNA mitocondrial indicam que as populações estão estruturadas geneticamente. The diversity of the sequence of the DNA of eight vulgaris populations of Octopus cf. vulgaris of the Brazilian coast and a population of Octopus vulgaris proceeding from Portugal was investigated by the use of the mitochondrial Cytochrome c oxidase subunit I (COI) gene. Approximately 600 bp of the mitochondrial COI gene were amplified by means of primers LCO1490 and HCO2198, purified and sequenced. The sequences were lined up by the ClustalW method. The phylogenetic tree generated by the alignment of the sequences of the COI revealed two main sets, forming monophyletic supported by bootstraps 93%. A clade containing the individuals proceeding from the Southeastern and South regions similar to the haplotypes of Portugal, which are classified as Octopus vulgaris, and another set formed by the individuals collected in several places of the North and Northeast regions. The level of the found genetic differentiation suggests the presence of two species of Octopus. As far as the population structure is concerned, the results found by the use of the nuclear DNA and the mitochondrial DNA indicates that the populations are genetically structured.

O objetivo desse trabalho foi avaliar a variabilidade genética de duas variedades de tilápia nilótica (Oreochromis niloticus), Chitralada e Red Stirling, e de suas progênies submetidas a programas de melhoramento genético, em sistemas intensivos de cultivo por meio de marcadores microssatélites. Foram utilizados 30 animais de cada variedade parental, 30 animais híbridos (CH), provenientes do cruzamento entre as variedades Chitralada e Red Stirling, e 30 animais (RR) provenientes do cruzamento entre os parentais da variedade Red Stirling. Utilizaram-se cinco microssatélites: UNH104, UNH108, UNH118, UNH222 e UNH231. Observaram-se baixos índices de endogamia, com valores de F IS negativo para as duas variedades e seus cruzamentos. Verificou-se diferença genética entre as duas variedades, obtida pelo cálculo do índice de fixação de alelos (F ST = 0,131 e R ST = 0,130). As variedades parentais Chitralada e Red Stirling apresentaram 24,4% de distância genética, o que se refletiu na presença de vigor híbrido com 23,5% de incremento em rendimento no plantel CH. The objective of this work was to evaluate the genetic variability of two Nile tilapia strains (Oreochromis niloticus), Chitralada and Red Stirling, as well as its offsprings submitted to genetic enhancement programs, in intensive systems farming by microsatellites markers. Thirty individuals of each parental strain, 30 crossbred (CH) individuals from Chitralada and Red Stirling strains, and 30 individuals from Red Stirling progeny (RR) were used. Five microsatellites loci were utilized: UNH104, UNH108, UNH118, UNH222 e UNH231. Low values of inbreeding were observed with a negative F IS in both strains and their crossings. Genetic differences between the two strains were detected through F ST = 0.131 and R ST = 0.130. The parental strains Chitralada and Red Stirling presented 24.4% of genetic distance, which produced 23.5% of hybrid vigor in the CH stock.