Genetic diversity of eleven European pig breeds

A set of eleven Dig breeds originating from six European countries, and inc luding a small sample of wild pigs, was chosen for this study of genetic di versity. Diversity was evaluated on the basis of 18 microsatellite markers typed over a total of 483 DNA samples collected. Average breed heterozygosi ty varied from 0.35 to 0.60. Genotypic frequencies generally agreed with Ha rdy-Weinberg expectations, apart from the German Landrace and Schwabisch-Ha llisches breeds, which showed significantly reduced heterozygosity. Breed d ifferentiation was significant as shown by the high among-breed fixation in dex (overall F-ST = 0.27), and confirmed by the clustering based on the gen etic distances between individuals, which grouped essentially all individua ls in 11 clusters corresponding to the 11 breeds. The genetic distances bet ween breeds were first used to construct phylogenetic trees. The trees indi cated that a genetic drift model might explain the divergence of the two Ge rman breeds, but no reliable phylogeny could be inferred among the remainin g breeds. The same distances were also used to measure the global diversity of the set of breeds considered, and to evaluate the marginal loss of dive rsity attached to each breed. In that respect, the French Basque breed appe ared to be the most "unique" in the set considered. This study, which remai ns to be extended to a larger set of European breeds, indicates that using genetic distances between breeds of farm animals in a classical taxonomic a pproach may not give clear resolution, but points to their usefulness in a prospective evaluation of diversity.