Genetic diversity and variability in Alpine sheep breeds

The aim of this study was to analyze, through the use of microsatellite molecular markers, the genetic diversity and variability of nine Alpine sheep breeds reared in Italy (Bergamasca, Biellese, Schwarzbraunes Bergschaf, Tiroler Bergschaf, and Schnalserschaf), Germany (Brillenschaf and Weisses Bergschaf) and Slovenia (Bovška and Jezerzkǒ-Solčavska), and one Italian crossbreed population. Allelic richness was rather high in each breed highlighting a considerable genetic diversity. However, the study evidenced a significant departure from Hardy-Weinberg equilibrium in all analyzed breeds caused by a heterozygote deficiency. Such lack seems to be caused both to the presence of population substructure within breed and to a rather high level of inbreeding. The genetic differentiation among breed was rather low (F ST =0.057) but significant. The clustering analysis performed with STRUCTURE detected the presence of eight clusters; Schwarzbraunes Bergschaf and Tiroler Bergschaf were grouped together and Biellese and Bergamasca as well, evidencing a high similarity of their genetic make up. Reynolds' genetic distance estimates confirmed the close relationship between these pairs of breeds. Moreover, Bovška, Jezerzkǒ-Solčavska and Brillenschaf resulted rather similar as expected according to their region of origin and to their common ancestors. Molecular coancestry confirmed as well such findings, suggesting that the studied breeds had origin from different ancestral populations. Concluding, microsatellite resulted a useful tool to investigate breed variability and to characterize Alpine sheep breeds. Obtained findings suggest the need to set up a conservation plan aiming to safeguard and increase the genetic variability of the studied breeds compromised by the high level of inbreeding. Microsatellites genotyping could help to monitor breed variability and to organize matings.