Resumo

LOPERA-BARRERO, NELSON M et al. Genetic Variability in Brycon orbignyanus Stocks Used in Stocking Programs: Management and Conservation. Acta biol.Colomb. [online]. 2008, vol.13, n.1, pp.107-118. ISSN 0120-548X.

Environmental alterations caused by the global heating and mainly caused by man's action, have reduced natural fish populations. As a conservation measure, stocking programs have been used; however, without scientific orientation these measures can generate genetic disturbances on the genetic diversity of natural fish populations and the ecosystem. The objective of this study was to estimate and analyze the genetic variability of Brycon orbignyanus stocks and offspring used in stocking programs, using the molecular marker RAPD (Random Amplified Polymorphic DNA). Fifty eight broodstocks of two stocks (A and C) and thirty offspring larvae of the stock A (B) belonging to the Estação de Aqüiicultura e Hidrologia da Duke Energy International (Geração Paranapanema; São Paulo, Brazil ) were analyzed. The results of genetic variability estimated by the Shannon Index diversity (A: 0.3184; B: 0.3433 and C: 0.3687) and for the percentage of polymorphic fragments (A: 54.02%; B: 57.47% and C: 58.62%) showed that the genetic variability was maintained in the offspring, due possibly to the appropriate reproductive management and the founder effect. On the contrary, the variability found among the two broodstocks indicates a genetic similarity, in spite of being natives of different fish farming's. This result is verified in the moderate value of genetic differentiation found (0.0968), in the high Nm (4.67) and the dendrogram, which suggests that the stocks hold a similar genetic pool.

Palavras-chave : Brazil; conservation; fishes; genetic variability; RAPD-PCR.

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