Abstract :
The knowledge of the genetic relationship and admixture among neighbouring populations
is crucial for conservation efforts. The aim of this study was to analyse the genetic diversity
of five Italian sheep breeds (Appenninica, Garfagnina Bianca, Massese, Pomarancina
and Zerasca) using a panel of 24 microsatellite markers. Blood samples from 226 individuals
belonging to the aforementioned populations were obtained and genotyped. All the
investigated breeds showed a significant heterozygote deficiency caused by the high level
of inbreeding indicated also by the high level of FIS (0.146). Genetic differentiation between
breeds was moderate (FST = 0.05) but significant and the individuals could be assigned to
their breeds with an high success rate even if the inter-individual distances showed that few
animals clustered separately from the other individuals of the same breed, especially for
Pomarancina breed. The genetic distances reflect the historical knowledge of these breeds
and some patterns of ancestral and recent gene flow between neighbour populations arise.
The clustering analysis detects the presence of six clusters. Massese and Zerasca breedswere
grouped together aswell as Appenninica and Pomarancina with the latter forming two distinct
clusters equally represented. The formation of this last breed is occurred with the
absorption of individuals of the Appenninica breed and the gene flow probably continued
in these recent years allowing the presence of a population substructure for Pomarancina
breed. Such substructure supports the high level of heterozygote deficiency found for this
breed despite the relatively high population size. The five populations analysed presented
some genetic similarities but a clear uniqueness of the populations has been showed for
almost all of them. Special attention to monitor genetic variability and to organize mating
plans should be given especially for the three endangered breeds.
