GENETIC-STRUCTURE OF 7 EUROPEAN CATTLE BREEDS ASSESSED USING 20 MICROSATELLITE MARKERS

Genotype data from 20 microsatellites typed in 253 animals is used her e to assess the genetic structure of seven European pedigree cattle br eeds. Estimation of genetic subdivision using classical drift-based me asures shows that the average proportion of genetic variation among br eeds Varies between 10 and 11% of the total, depending on the estimato r used. We demonstrate that a simple allele-sharing genetic distance p arameter can be used to construct a dendrogram of relationships among animals. This phylogenetic tree displays a remarkable degree of breed clustering and reflects an extensive underlying kinship structure, par ticularly for the Swiss Simmental breed and four breeds originating fr om the British Isles. Condensation of allele frequencies and individua l genotypic: compositions using principal component analysis is also u sed to investigate genetic structure among breeds and individual anima ls. In addition, the underlying genetic demarcation of European cattle breeds is emphasized in simulations of breed assignment using allele frequency distributions from samples of microsatellite loci. Correct b reed designation can be inferred with accuracies approaching 100% usin g data from a panel of 10 microsatellite loci.