Estrutura populacional e diversidade genética de raças bovinas brasileiras localmente adaptadas

Abstract

As the aim of investigating the population structure of Brazilian bovine locally adapted breeds, 237 individuals from Caracu (n = 50), Creole Lageana (n = 39), Curraleira (n = 50), Mocha Nacional (n = 50) and Pantaneira breeds (n = 48) were genotyped with 28 microsatellite loci chosen from lists of FAO / ISAG and BIOBOVIS project. Indices of genetic diversity were calculated by FSAT program and the genetic population structure was obtained based on Bayesian analysis implemented by the STRUCTURE program. There was a significant genetic differentiation (p <0.05) between breeds studied, the percentage of variation among populations was 4.64%. In general the expected heterozygosity was higher than observed heterozygosity (0.751 vs 0.696). The Creole Lageana breed showed the highest allelic richness (8.9) while the lowest was observed in the Caracu breed (7.07). The greatest FIS was observed in Curraleira (0.106) and the smallest in the Mocho National (0.035). By the Bayesian analysis one could observe that Curraleira and Pantaneira breeds share the largest number of alleles while Caracu quickly distinguished from the others. The results are consistent with the history of the formation of these populations after their introduction in Brazil by the colonizers. Moreover, it appears that populations which are inserted in breeding programs, such as Caracu, have less genetic diversity when compared with the other, although this does not necessarily reflect an increase of inbreeding in the population. In Curraleiro breed high levels of inbreeding may reflect the need for exchanges between the different breeding farms sampled.