Genome-Wide Characterisation of the Ashanti Dwarf Pig Within a Global Context: Insights into Diversity, Inbreeding, and Adaptive Signatures

Abstract

Indigenous pig breeds represent valuable reservoirs of genetic diversity but face increasing risks of genetic erosion due to uncontrolled crossbreeding with commercial lines. The Ashanti Dwarf Pig (ADP) of Ghana is an important local genetic resource well-adapted to tropical environments but poorly characterised at the genomic level. Using high-density SNP data from the ADPs and publicly available datasets from other African, European, and Asian pig populations, we examined genetic diversity, population structure, inbreeding, and selection signatures. After quality control, 59,124 SNPs across 875 individuals were retained. ADPs exhibited high polymorphism (~99%) and moderate heterozygosity but also elevated inbreeding (FIS = 0.15; FROH = 0.40), indicating recent inbreeding under free-range management. Population structure revealed that ADPs cluster closely with other African pigs and European breeds more than Chinese breeds. ADMIXTURE analysis, however, indicated recent introgression from both European and Chinese lines. Selection scans revealed candidate genes linked to metabolism-Zinc Finger Ran-Binding Protein 3 (ZRANB3), growth-Sortilin Related VPS10 Domain Containing Receptor 1 (SORCS1), reproduction–Sus Scrofa Chromosome 9 quantitative trait loci (SSC9 QTLs), and immunity-Tudor Domain-Containing Protein 3 and CKLF-like MARVEL transmembrane Domain Containing 7 (TDRD3, CMTM7), reflecting adaptation to tropical production systems. Our results provide a comprehensive genomic characterisation of the ADP within a global context, revealing both genetic richness and vulnerability to genetic erosion. These findings underscore the importance of structured breeding and conservation strategies in preserving this unique African genetic resource and supporting sustainable pig production under changing climatic conditions.