Genome-wide association study identifies candidate genes for body size and establishes a core germplasm set in Duoma sheep

Duoma sheep ( Ovis aries ) are an indigenous breed native to the Tibetan Plateau, where they have adapted to extreme high-altitude conditions. To elucidate the genetic architecture of body size in Duoma sheep, we performed whole-genome resequencing of 195 animals and conducted a GWAS for six phenotypic traits, together with the development of a core germplasm set. At an exploratory significance threshold of −log10( p ) ≥ 6, we detected 330 trait-associated SNPs across the six phenotypes. Body weight yielded 74 associations (mapping to 80 candidate genes), the second largest after body length (207 SNPs, 228 genes), followed by chest girth (21 SNPs, 18 genes); chest depth and body height showed fewer associations (16 and 8 SNPs, respectively), while chest breadth exhibited only four associated SNPs with no annotated genes in the flanking regions. Candidate genes of interest include GPR84 , SRFBP1 , and RUVBL1 for body weight; EXOC1 and ZC3H14 for body length; and SOCS2 and SMAD6 for chest girth. Population structure analyses indicated a genetically homogeneous background with rapid linkage disequilibrium decay, reinforcing the robustness of the association signals. In addition, a core collection comprising 39 accessions (20% of the full population) was constructed, which effectively retains the genetic diversity of the entire sample set. Collectively, these results provide a valuable genomic resource for the conservation and molecular breeding of Duoma sheep.