Whole genome sequencing revealed genetic diversity, population structure, and selective signature of Tianhua mutton sheep.

backgroundSheep have diversified into distinct breeds worldwide through both natural adaptation and human-driven selection, with hybridization serving as an effective strategy for rapid trait improvement. The Tianhua mutton sheep (TMS) is a novel breed derived from crossing South African Mutton Merino (SAMM) with Gansu alpine fine-wool sheep (GAFS). After nearly two decades of selective breeding, TMS has developed great meat quality traits and impressive cold tolerance at high altitudes. To study the genetic mechanism and provide new insights into phenotypic variation, we analyzed the genetic diversity, population structure, and selective signatures of TMS based on whole-genome sequencing of 55 TMS, 11 SAMM, and 197 public sheep genomes worldwide.

resultsPopulation genetic analysis revealed that TMS forms a distinct branch, with a pedigree composition showing an approximate 5:3 ratio of SAMM to GAFS lineages, consistent with the breeding design. Genetic diversity assessment showed that TMS exhibits higher genetic diversity and a lower inbreeding coefficient than commercial sheep from Africa, the Americas, and Europe, suggesting that TMS has considerable breeding potential to be tapped. Genome-wide scanning using the F

conclusionThe results provide valuable insights for investigating the genetic mechanisms underlying TMS fine traits, enhancing TMS breeding, and developing mutton sheep suited to high-altitude and cold environments. Furthermore, it also indicates that hybrid breeding represents an effective strategy to provide a source of phenotypic variation for local adaptation and rapid acquisition of agronomically important traits.