Genome-wide SNP data unravel the ancestry and signatures of divergent selection in Ghurrah pigs of India

Abstract

The evolution and domestication of pigs is a complex and ongoing process. Despite its rich biodiversity and proximity to the geographical origins of Sus scrofa domesticus, the place of Indian pigs in the global phylogeny is unclear. Using microarray-derived (porcine 60K SNP chip) genotypes of 11 Ghurrah pigs from North-Western India and a public dataset comprising 2113 pigs of 146 breeds, we determined the genomic ancestry of Ghurrah pigs and compared their genetic constitution to European and Asian breeds to ascertain signatures of divergent selection. Results showed that Ghurrah pigs contain genes of Asian and European ancestry with signs of inter-species introgression. Using Admixture LD – decay statistics, the European admixture event was dated to the recent past, coinciding with the start of cross-breeding efforts in India. The complex Asian ancestry pattern of the breed resembled that of wild boars of South – Central China and Thailand, possibly suggesting introgression from an Indian wild boar relative. Signatures of selection analysis showed the divergence of Ghurrah pigs from Asian and European breeds in genomic regions associated with odontogenesis, and nervous system processess, respectively. Our results present the first genomic characterization of an Indian pig breed using dense microarray-derived genotypes and highlight the importance of further genomic characterization of Indian domestic and wild pigs. Given the limited sample size available for this study, validation of the findings in a larger population is suggested.