BACKGROUND: Yanyun (YY) sheep are a composite breed developed by targeted crossbreeding of Dorper, Hu, and East Friesian sheep to improve growth, reproduction, and environmental adaptability, yet the genomic basis underlying their formation and selective improvement remains unclear. RESULTS: Whole-genome analyses showed that YY sheep retain moderate genetic diversity with low genomic inbreeding (FROH), indicating limited autozygosity. Population structure analyses supported that YY sheep form a genetically distinct yet admixed group consistent with their breeding history. Genome-wide selection scans identified multiple candidate regions associated with growth, metabolism, reproduction, immune function, and environmental adaptability, including loci showing consistent differentiation and haplotype-based selection signals across multiple population comparisons. CONCLUSIONS: These results provide a genome-wide view of the genetic diversity, population structure, and selection landscape of YY sheep, and identify candidate genomic regions for future investigation of economically important and adaptive traits in composite sheep breeding.
Yang et al. (Wed,) studied this question.