Genetic characteristics of Tambaqui broodstocks in the state of Rondônia, Brazil: implications on production and conservation

Abstract

In recent years, the genetic monitoring of broodstocks in fish farming has been greatly highlighted due to its importance in the management and improvement of their production and conservation. Current study evaluates the genetic diversity of four Tambaqui broodstocks (Colossoma macropomum) in the state of Rondônia (Brazil) and discusses activities towards the species´s correct production management and conservation. Nine primers were employed to analyze 94 specimens from four fish farms in the municipalities of Ji-Paraná (JP), Ouro Preto do Oeste (OP), Presidente Médici (PM) and Rolim de Moura (RM). Differences in the frequency of 38 fragments, with an exclusive fragment in JP and OP, were reported. High polymorphism (52.40 to 64.60%) and Shannon Index (0.313 to 0.382) rates were observed. The analysis of molecular variance (AMOVA) demonstrated that most variation is within each stock. The identity and genetic distance between the groups ranged between 0.927 and 0.954 and between 0.047 and 0.076 respectively, with shortest distance between the OPxPM and JPxRM groups. Genetic differentiation ranged from moderate to high (Fst = 0.081 to 0.179) and the number of migrants per generation was moderate (Nm = 3.83 to 6.24). As a rule, stocks showed high genetic variability and moderate / high differentiation and genetic distance between them. The results allowed direct conservation programs and increase the productivity of this species in fish farming through breeding programs.