How to better conserve with genetic data: origin and population structure of Brazilian locally adapted hair sheep (Ovis aries) breeds

Abstract

Brazilian hair sheep constitute a genetic diversity hotspot of sheep breeds. These locally adapted genetic resources developed in harsh environments of the Brazilian Northwest (semi-arid) and maintained important traits for this region, such as parasite resistance, heat tolerance and high pelt quality. Genotypes (50K SNP chip) from seven Brazilian sheep breeds (5 hair and 2 coarse wool types) and 87 worldwide breeds were used to verify population structure, admixture and genetic diversity, using PCA and ADMIXTURE analyses. We constructed a phylogenetic tree and evaluated migration events between genetic groups using TREEMIX software. Brazilian Somali, a fat-tailed breed, was the unique breed with high relationship with East African breeds and formed a distinct cluster from other Brazilian breeds. This breed seems to contribute to formation of Santa Ines, Morada Nova and Brazilian Fat-tail breeds. Brazilian Blackbelly had a clear relationship with Barbados Blackbelly, which appeared as another group. Other Brazilian breeds seem to form a further genetic group with some recent admixtures. Morada Nova remained as a separate group, not showing a strong relationship with European or African breeds, only revealing a migration event from Sidaoun, an Algerian hair breed. Brazilian Fat-tail and Morada Nova share a common ancestor, but the first received introgressions from Brazilian Somali and Afrikaner breeds, explaining the fat-tail phenotype. Santa Ines received strong contribution from Bergamasca and had an admixed origin with recent introgressions from other breeds, mainly from Suffolk animals. In conclusion, Brazilian Somali and Brazilian Fat-tail are the most endangered sheep genetic resources in Brazil.