GWAS and selection signature analyses of whole-genome sequencing data identify genes associated with body size in Duolang sheep
Introduction Duolang sheep is a meat-fat dual-purpose breed originating from Xinjiang, China, and the genetic basis of body size variation in this breed remains unclear. Methods Whole-genome resequencing was performed on 224 Duolang sheep with complete records for six body size traits. After variant calling, imputation, and quality control, 19.65 million high-quality SNPs were retained. After linkage disequilibrium pruning, 2.1 million relatively independent SNPs were used for a mixed linear model GWAS in GEMMA. Tajima’s D and integrated haplotype score analyses were performed in a kinship-filtered subset of 60 animals, and SheepGTEx data were used to characterize tissue expression patterns. Results The GWAS identified 24 significant SNPs for height, body length, chest girth, shoulder width, and hip width. Integration of GWAS intervals with selection-signal regions prioritized 31 candidate genes, including CA10, WDR45B, FADS2, LGALS12, and CTNNA2. Multi-tissue expression profiles provided functional context for the prioritized genes. Discussion These findings provide insight into the genetic architecture of body size traits in Duolang sheep and identify candidate loci for future validation and genetic improvement studies.