Genetic variability and structure of three tunisian ovine breeds based on microsatellite polymorphism

Genetic diversity of native ovine Barbarine (BR=80) and Queue Fine de l'Ouest (QF=150) breeds as well as the exotic D'man (DM=70) breed were investigated using a panel of ten microsatellite markers. The markers used were all polymorphic and exhibited high levels of polymorphism. The total number of observed alleles across all breeds was 83. The allelic frequency distribution was heterogeneous and tests of genotype frequencies for deviation from HWE revealed significant departure from HWE of all populations for the TGLA48 and MCM527 loci. The mean expected and observed heterozygosity for the BR, QF and DM populations varied from 0.69 to 0.74 and 0.58 to 0.67, respectively. The average Polymorphism information content (PIC) was 0.683, 0.699, 0.697 and 0.657 for BR, QFG, QFT and DM, respectively. The mean F (ST) was 0.149 and indicated that most (85.1%) of total genetic variation raised from differences among individuals and only 14.9% came from differences among breeds. Per pair estimator of F(ST) indicated a low to moderate differentiation between BR and QF but a relatively high (F(ST) > 0.15) differentiation between Tunisian native (BR and QF) and DM breeds. Genetic distance and factorial analyses showed that genetic distances observed between BR-DM and between QF-DM were larger than those found between BR-QF breeds.