Genetic Variability of Brycon hilarii in a Repopulation Program

ABSTRACT Brycon hilarii, popularly called piraputanga in Brazil, is a species distributed throughout the whole basin of the river Paraguay. In recent years, the species has been on a repopulation program due to its remarkable decline as a wild species in the region. Assessment of the genetic diversity of broodstock and fingerling stocks in repopulation programs is basic to avoid genetic impacts on wild populations. The genetic variability of the wild population and of the broodstock and fingerling stocks of B. hilarii in a repopulation program in the river Itiquira MT Brazil will be determined. Seven microsatellite loci produced 52 polymorphic alleles and heterozygosity revealed rates between 0.5794 and 0.7204. FIS did not register any endogamy in the broodstock but it was present in fingerlings and wild populations. Intra- and inter-specific genetic variability rates were higher within each combination but not between groups. Grouping in fingerling groups had a lower density when compared to the others. There is a higher genetic proximity between the natural population and broodstock (0.0237) when the distance between populations was analyzed, even though the two were greatly distant from the fingerling group (0.2622 - 0.2617). Results show that the wild population and the broodstock had high genetic variability and low genetic divergence; contrastingly, fingerlings showed mild genetic variability and great divergence when compared to other groups, indicating that they were not adequately constituted.

Diversidade genética de quatro linhagens de Oreochromis miloticus utilizando o marcador RAPD / Genetic diversity of four Oreochromis niloticus strains using the RAPD marker

O objetivo do presente estudo foi analisar a diversidade genética de quatro linhagens de tilápia do Nilo (Oreochromis niloticus), utilizando o marcador RAPD. Foram coletadas amostras de nadadeira de estoques de juvenis das linhagens GIFT (G), Chitralada (C), Supreme (S) e Bouaké (B). Os 11 primers utilizados produziram 81 fragmentos dos quais 41,98% foram polimórficos. A porcentagem de fragmentos polimórficos (G: 18,52%; C: 19,75%; S: 20,99% e B: 24,79%) e os resultados do Gst confirmaram que houve alta (BxG: 0,231; BxC: 0,224; GxC: 0,194 e SxC: 0,208) e elevada (BxS: 0,315 e GxS: 0,270) diferenciação genética entre as linhagens. O fluxo gênico (Nm) foi maior entre as linhagens GxC (2,082). Os valores de distância e identidade genética (0,044 e 0,957 respectivamente) e o dendrograma indicam que as linhagens GxC são os mais semelhantes geneticamente. A similaridade genética foi alta dentro das linhagens (G: 0,932; C: 0,903; S: 0,891 e B: 0.900). Os resultados deste estudo possibilitarão o correto manejo reprodutivo e genético das linhagens.

The aim of this study was to analyze the genetic diversity of four Nile Tilapia (Oreochromis niloticus) strains using the RAPD marker. Fin samples of GIFT (G), Chitralada (C), Supreme (S) and Bouaké (B) juvenile stocks have been collected. The 11 primers used yielded 81 fragments of which 41.98% were polymorphic. The percentage of polymorphic loci (G: 18.52%; C: 19.75%; S: 20.99% and B: 24.79%) showed that there was a genetic differentiation among the strains, showing the Gst values a high (BxG: 0.231; BxC: 0.224; GxC: 0.194 and SxC: 0.208) and elevated (BxS: 0.315 and GxS: 0.270) differentiation. The highest gene flow (Nm) was among the GxC (2.082) strains. The distance and genetic identity values (0.044 and 0.957 respectively) and the dendrogram indicate that the GxC is the most genetically similar strains. The genetic similarity was high among of the strains (G: 0,932; C: 0,903; S: 0,891 AND B: 0.900). These results will enable a correct reproductive and genetic strains management.

Caracterização genética de estoques de Prochilodus lineatus(Valenciennes, 1836) (Characiformes: Prochilodontidae), utilizados em programas de repovoamento: importância para a conservação da ictiofauna e do ecossistema / Genetic characterization of Prochilodus lineatus (Valenciennes, 1836)

Alterações ambientais provocadas pelas mudanças climáticas e principalmente por ações humanastêm reduzido populações naturais de peixes nos últimos anos. Os programas de repovoamento têm sido utilizados como forma de conservação, porém, sem uma correta orientação científica essas medidas podem gerar distúrbios sobre a diversidade genética da ictiofauna e sobre o ecossistema. O objetivo deste estudo foi analisar a diversidade genética de dois estoques de alevinos de Prochilodus lineatus utilizados em programas de repovoamento, mediante o marcadormolecular RAPD. Foram analisados 60 alevinos (estoque A e B) de uma piscicultura localizada no município de Rolândia, PR (Brasil). Os sete iniciadores selecionados produziram um total de 77 fragmentos, dos quais 81,82% foram polimórficos. Os valores de variabilidade genética estimados pela porcentagem de fragmentos polimórficos (A= 83,12%;B= 81,82%) e pelo índice de diversidade genética de Shannon (A= 0,473; B= 0,463) mostraram que não existe uma alta diferenciação genética entre os dois estoques, possivelmente devido ao efeito fundador e ao manejo reprodutivo. Este resultado foi corroborado com o valor de Gst (0,043), do dendrograma e da distância e identidade genética (0,967 e 0,034)que mostram uma baixa diferenciação genética entre eles. Os resultados deste estudo possibilitarão o correto manejoreprodutivo e genético dos estoques e a orientação objetiva de programas de repovoamento, permitindo a conservação da ictiofauna e dos ecossistemas impactados.

Environmental alterations caused by the climatic changes and mainly for human actions, it hasbeen reducing fish natural populations in the last years. The stocking programs have been used as conservation form,however, without a correct scientific orientation those measured can generate disturbances about the genetic diversity of the ichthyofauna and on the ecosystem. The objective of this study was to analyze the genetic diversity of two juvenile Prochilodus lineatus stocks used in stocking programs, by the RAPD molecular marker. Sixty juvenile (A and B stocks) of a fish farm located in the Rolândia Municipal District, PR (Brazil) were analyzed. The seven primers selected produced a total of 71 fragments, of which 89.44% were polymorphic. The genetic variability values estimated by the percentage ofpolymorphic fragments (A = 83.12%; B = 81.82%) and for the genetic diversity of Shannon index (A = 0.473; B = 0.463) showed that a high genetic differentiation doesn't exist among the two stocks, possibly due to the founder effect and the reproductive management. This result was corroborated with the Gst value (0.043), of the dendrogram and of the distance and genetic identity (0.967 and 0.034) that show a low genetic differentiation among them. The results of this study will make possible the correct reproductive and genetic management stocks and the objective orientation at of stocking programs, allowing the ichthyofauna and the impact ecosystems conservation.