Exploring the Polygenic Landscape of Wool Traits in Turkish Merinos Through Multi-locus GWAS Approaches: Middle Anatolian Merino

Abstract The study investigates the genetic architecture of fibre diameter (FD) and staple length (SL) in Middle Anatolian Merino sheep using multi-locus genome-wide association study (GWAS) approaches. Heritability and variability analyses revealed contrasting patterns: FD showed moderate heritability (h² = 0.461) with low variability (CV = 7.570%), while SL exhibited low heritability (h² = 0.191) but high variability (CV = 24.437%). Genetic correlations indicated moderate positive relationships between FD and certain growth traits (rG = 0.385–0.455, p < 0.001), whereas SL showed weak, non-significant correlations with these traits. The correlation between FD and SL was also weak and non-significant (rG = -0.043, p = 0.383). Using four multi-locus GWAS methods (mrMLM, FASTmrMLM, FASTmrEMMA, and ISIS EM-BLASSO), which can detect polygenic effects on complex traits like wool quality, 18 SNPs for FD (7 co-detected) and 14 SNPs for SL (5 co-detected) were identified across multiple chromosomes. Post-hoc power analysis demonstrated strong statistical power for both traits (FD: 0.95, SL: 0.91). These results could guide future breeding strategies aimed at optimising both wool quality and growth performance. Further research is needed to validate these findings in other populations and to explore the biological relevance of the identified genomic regions.