An historical and biogeographical assessment of European Merino sheep breeds by microsatellite markers

Although the Merino breed originated in the Iberian Peninsula, the Merino and Merino-derived sheep breeds have nowadays been widely distributed across the world both as purebreds and as admixed populations. In Europe, the Merino trunk has both high phenotypic and genetic diversity which originated from several genetic types adapted to different economic and farming environments. For these reasons, Merino and Merino-derived breeds must be presently considered cosmopolitan breeds that have an important role worldwide in the production of high-quality wool. This paper presents the results of the genetic characterization by 35 STR markers of 539 animals which are the most important 16 Merino and Merino-derived sheep breeds in Europe. The results highlighted a remarkable level of genetic variability in all breeds. Overall, microsatellite polymorphism analysis revealed the Merino Pozo Blanco as the most homogeneous breed. The subdivision between the studied breeds was shown by the STRUCTURE analysis even though a genetic admixture is particularly evident in the three Italian Merino derived breeds. In this study, the historical background of the Merino breed has been assessed from the genetic point of view, and the Spanish origin of the Merinos branch seems to be confirmed. In general, despite their common ancestral origin, nowadays the investigated Merino and Merino-derived breeds present a genetic identity in accordance with their geographical location probably due to different selection strategies.