A comprehensive survey of genetic variation of Italian sheep breeds at 50 K SNP loci : implications for breed management and conservation

The objective of the study was to perform a comprehensive survey of genetic variation in Italian sheep breeds through high-throughput SNP genotyping in order to provide population genetics data that may be useful in orienteering management and conservation actions. A set of 496 animals, representative of 20 sheep breeds/populations evenly distributed all along the Italian peninsula were genotyped at the Ovine SNP50 BeadChip . The most widespread dairy and meat breeds as well as some of the most endangered breeds were included in the study. SNP loci resulted to be a very powerful tool to finely reconstruct both known and hidden breed relationships, also allowing differentiating among ancient and more recently admixed population groups through sharing analysis of varying window size haplotypes. The Multi Dimensional Scaling (MDS) analysis generally highlighted a clear and continuous geographical gradient in the genetic diversity pattern; this result suggests a major role for short/ medium-range admixture in shaping modern-day breed genetic background, consistently with historically extensive sheep farming practices and seasonal transhumance movements. A major exception was represented by the introgression of Bergamasca (Northern Italy) into Appenninica (Central Italy), as clearly highlighted by SNP data. Analyses are still under way in order to detect possible selection signatures. Once completed, the study will provide a better understanding on amount, distribution and functional significance of genetic variation in Italian sheep breeds that may contribute to more efficient management, conservation and valorisation of Italian sheep genetic resources.