A Genome-Wide Scan for Signatures of Selection in Kurdish Horse Breed.
Authors: Nazari Faezeh, Seyedabadi Hamid-Reza, Noshary Alireza, Emamjomeh-Kashan Nasser, Banabazi Mohamad-Hosein
Journal: Journal of equine veterinary science
Summary
Kurdish horses have undergone significant population bottlenecks in recent history, with effective population size declining sharply approximately four generations ago to around 104 individuals, whilst evidence of inbreeding stretches back roughly 20 generations—a demographic pattern that warrants careful management of this breed's genetic resources. Using genomic analysis of 72 Kurdish horses genotyped with SNP arrays, researchers identified multiple chromosomal regions bearing signatures of selection, with particular concentration on equine chromosome 9 (ECA9), where 40% of significant selection signals clustered in regions associated with withers height and overall body size. Two additional hotspot regions on ECA7 and ECA11 showed evidence of strong selection pressure in at least 30% of the population, harbouring quantitative trait loci linked to stature, alternative gaits, and insect bite hypersensitivity—traits likely shaped by both natural adaptation to the Kurdish environment and deliberate breeding preferences. For practitioners working with these horses, this research suggests that morphological characteristics such as frame size and coat traits have been substantially shaped by selective pressures, whilst the documented inbreeding coefficient (0.047) indicates breeders should prioritise genetic diversity management to prevent accumulation of deleterious recessive alleles. Future functional validation of these genomic signatures would clarify which traits represent adaptive responses to local conditions versus unintended consequences of restricted breeding populations, informing more strategic breeding programmes.
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Practical Takeaways
- •Kurdish horse breeders should be aware of recent inbreeding and declining effective population size; consider genetic management strategies to maintain diversity and reduce risk of recessive trait expression
- •Selection signatures on body size and alternate gait loci suggest these traits have been under breeding pressure; continued monitoring may help maintain desired phenotypes while managing genetic health
- •High frequency of insect bite hypersensitivity associations in genomic regions indicates this may be a genetically predisposed condition in Kurdish horses; management should focus on environmental controls and early intervention strategies
Key Findings
- •Effective population size of Kurdish horses was 104 individuals up to three generations ago with average inbreeding coefficient (FROH) of 0.047, indicating recent population contraction
- •Genome-wide scan identified 148 significant SNPs under putative selection (FDR < 0.05), with 40% located on ECA9 associated with withers height and body size
- •Two hotspot regions on ECA7 (50.11-54.36 Mbp) and ECA11 (26.10-29.07 Mbp) present in ≥30% of individuals harbor QTL for withers height, alternate gaits, and insect bite hypersensitivity
- •Genomic signatures of selection identified for phenotypic traits including coat texture, hair density, temperament, and gastrointestinal conditions