Resumen

LOPERA BARRERO, Nelson Mauricio et al. Genetic diversity of Brycon orbignyanus in the semi-natural reproductive system, using the RAPD marker. Zootecnia Trop. [online]. 2010, vol.28, n.1, pp.73-82. ISSN 0798-7269.

The stock enhancement programs are being used more frequently as methods of fish conservation. However, the genetic monitoring and the reproductive procedures evaluation are necessary to achieve viable and reliable results. The purpose of this study was to analyze the genetic diversity of Brycon orbignyanus used in stock enhancement programs, in the semi-natural reproductive system, with the RAPD marker. Fifteen broodstocks (10 male and 5 female) and 95 larvae of the offspring were analyzed. The semi-natural reproductive system allowed the obtaining of a low mortality of the broodstocks using in the mating and all presented spawing/spermiation. The nine primers used yielded 90 fragments, of which 73,33% were polymorphic. Differences (P <0,05) in the frequency of 17 fragments were observed, without the presence of exclusive fragments. The Shannon genetic diversity index and percentage of polymorphic fragments were lower in the offspring individuals. Genetic similarity was higher in the offspring. The analysis of molecular variance results showed that the major part of the genetic variation is within the groups (81,49%) and not between them (18,51%). The identity and genetic distance among the groups were 0,953 and 0,049; respectively. In spite of the semi-natural reproductive system to allow the decrease of mortality and an appropriate reproductive broodstocks behavior, was decrease of the genetic variability in the offspring for the effect of the small number of broodstocks used during the reproduction and for the low existent genetic variability among them

Palabras clave : Brazil; fish; genetic conservation; genetic variability; RAPD-PCR; stock enhancement programs.

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