Genetic characterization of Gift tilapia generations using microsatellite markers

Resumo

The objective of this work was to characterize the genetic variability in parental (G₀) and three subsequent generations (G₁, G₂ and G₃) of genetically improved farmed tilapia (Gift) using microsatellite markers. Three hundred sixty individuals from the breeding program of Universidade Estadual de Maringá, PR, Brazil, were selected for weight gain. A total of 21 alleles was found in all five polymorphic microsatellite loci (G12292, UNH140; G12311, UNH159; G12312, UNH160; G12314, UNH162; and G12315, UNH163), with an average number between three and five alleles per locus. Allele frequencies ranged from 0.017 (UNH160 – G₂) to 0.750 (UNH160 – G₀). The average observed heterozygosity was 0.501, 0.391, 0.531, and 0.503 for G_0, G₁, G₂ and G₃, respectively. The average inbreeding coefficient was 0.192 (G₀), 0.401 (G₁), 0.230 (G₂), and 0.301 (G₃). All generations showed deviation from Hardy‑Weinberg equilibrium, with linkage disequilibrium in most loci. Except for G₁, the heterozygosity was maintained in the G₂ and G₃ generations, which indicates that there is no significant loss of genetic variability in the breeding program.