Genetic diversity of Tambaqui (Teleostei - Characidae) broodstocks from Northern region of Brazil using microsatellite markers

The Amazonian fish Tambaqui (Colossoma macropomum) is the most common native species in Brazil. This species has the highest production rate in the Northern region, especially in the State of Rondonia. The genetic evaluation of Tambaqui is an extremely important to increase productivity in fish farms or improve the adaptability in restocking natural populations. The objective of this study was to evaluate the genetic diversity of three Tambaqui broodstocks in Rondonia. Brazil. Six microsatellite markers were used to analyze a total of 89 breeders collected from three fish farms located in Ji-Parana (JP), Ouro Preto do Oeste (OP) and Presidente Medici (PM). A total of 37 alleles between 140 and 310 bp were found, including the presence of exclusive and low frequency alleles in the three broodstocks. The average values of observed heterozygosity ranged from 0.404 (PM) to 0.499 (JP). The F-IS coefficient values were positive for the three broodstocks, demonstrating a deficit of heterozygotes. The Molecular Variance Analysis (AMOVA) showed greater variation within the stocks than between them. The genetic differentiation was moderate and significant between the stocks, with higher differentiation between JP x PM and lower between OP x PM. The Bayesian analysis designated an optimal value of K = 3 groupings. Although there is moderate genetic diversity between broodstocks, the high F-IS indicates a possible decline of diversity in the next generations, and therefore, the incorporation of new breeders is suggested to increase the genetic diversity in the three stocks.