Abstract

LOPERA-BARRERO, N. Mauricio et al. Genetic diversity in Piaractus mesopotamicus stocks used in stock enhacement programs and implications for conservation. Agrociencia [online]. 2009, vol.43, n.3, pp.249-256. ISSN 2521-9766.

Environmental changes caused principally by human action have provoked reduction and even disappearance of several populations of fish. To minimize this impact stock enhancement programs are being implemented in several Brazilian states. However, without adequate evaluation, these programs can produce genetic changes in populations of native fish. Therefore the objective of this study was to analyze, with the RAPD molecular marker, the genetic diversity of Piaractus mesopotamicus stocks used in stock enhancement programs. One hundred twenty broodstocks at four fish farm stations located in the Sapopema (S), Cornélio Procópio (CP), Cambará (C), and Londrina (L) cities, in the Paraná state, Brazil, were analyzed. The results of genetic variability determined using the percentage of polymorphic fragments (S = 74.15 %; CP=78.80 %; C = 77.61 %; L=92.90 %) and the Shannon genetic diversity index (S=0.381, CP=0.422; C = 0.438; l=0.522) showed high genetic variability in all of the broodstocks. However, high genetic similarity was found between the S, CP, and P stocks possibly due to the founder effect since the stocks were founded with broodstocks collected in the Paraná River. The result was corroborated with Gst values and gene flow, which showed moderate genetic differentiation and high gene flow. The broodstock from L had a greater genetic distance from the other stocks because it was founded with broodstocks collected in the Paranapanema River. It was also confirmed that the broodstocks CP and C were the most genetically similar (genetic identity-GI=0.954) and the S and L broodstocks had less genes in common (GI=0.692). The L stock was the most distant of all the broodstocks.

Keywords : Genetics of conservation; fish; Piaractus mesopotamicus; RAPD; stock enhancement; genetic variability.