Revealing the Shared Genetic Basis of Thermal Adaptation and Abdominal Adiposity in Wenchang Chicken Using Whole-Genome Structural Variation Analysis

Environmental temperature significantly influences the evolutionary adaptation of poultry, while abdominal fat deposition represents a crucial economic trait affecting feed conversion efficiency and carcass quality. However, reports on the genetic mechanisms governing their co-evolutionary trade-offs remain scarce. This study employed whole-genome resequencing data from 469 chickens across 31 varieties. Through comparative analyses of heat- versus cold-adapted groups and high- versus low-fat groups, structural variations (SVs) were utilized as genetic markers. Selection signatures were identified via the population differentiation index (FST) and nucleotide diversity ratio (π ratio). We identified 103 overlapping genes located within significantly differentiated SVs at the intersection of temperature adaptation and fat deposition. Pathway analysis revealed significant enrichment in the thyroid hormone signaling pathway, pinpointing MED17 as a key selection target. Further validation via PCR genotyping in the heat-tolerant Wenchang chicken revealed that individuals harboring the MED17 mutation exhibited significantly higher abdominal fat deposition than those without. These results suggest that MED17 is associated with fat deposition in heat-tolerant Wenchang chickens, serving as a potential candidate gene for this trait, providing robust molecular markers for breeding novel strains with both thermotolerance and superior carcass traits.