Genetic diversity of Piracanjuba populations in fish stocking programs in the Tietê River, Brazil

Abstract

Background: Piracanjuba (Brycon orbignyanus) is a fish species highly affected by anthropogenic actions such as overfishing, water pollution, and hydroelectric developments. This species is currently considered in danger of extinction. Objective: To analyze the genetic diversity of a natural population (NP) and two captive broodstocks (SA and SB) of B. orbignyanus. Methods: Samples of caudal fins (NP: 24, SA: 30, and SB: 30) were collected. DNA was extracted and amplified for six RAPD primers and four microsatellite loci. Results: Sixty polymorphic fragments and 17 microsatellite alleles were detected. High intrapopulation heterozygosity (NP: 0.692, SA: 0.724, and SB: 0.686) was observed. Thirty-eight fragments and six alleles were shared among NP, SA, and SB. The FIS and Shannon’s Index of diversity revealed a lack of inbreeding within groups. AMOVA analyses and FST indicated very high (NP vs SA and SB) and small (SA vs SB) genetic differentiation, confirmed by genetic distance and identity, number of migrants and a dendrogram, which revealed the formation of two genetic groups. Conclusions: The two marker types showed similar variability. The groups have adequate genetic variability, with high differentiation between NP and SA–SB, and similarity between broodstocks.