Selection signatures in four German warmblood horse breeds: Tracing breeding history in the modern sport horse.
Authors: Nolte Wietje, Thaller Georg, Kuehn Christa
Journal: PloS one
Summary
# Editorial Summary German warmblood breeds have been shaped by distinct breeding philosophies, yet little was known about which genomic regions have experienced the strongest selective pressure across these populations. Researchers analysed 942 stallions from four breeds (Trakehner, Holsteiner, Hanoverian and Oldenburger) using SNP genotyping and multiple statistical approaches to identify selection signatures—genomic regions harbouring genes influencing performance traits. Whilst Oldenburger and Hanoverian breeds displayed remarkably similar selection patterns, breed-specific differences emerged across multiple chromosomes, with Trakehners showing the highest genomic homozygosity owing to historical population bottlenecks; across all breeds, however, shared selection signals clustered on chromosomes 1, 4 and 7, implicating genes regulating muscle function, energy metabolism, growth, reproduction and coat colour. These findings suggest that despite divergent recent breeding goals—Holsteiners emphasising show-jumping, others favouring eventing or dressage—modern warmblood selection has consistently targeted biological pathways fundamental to athletic performance and fertility. For breeding professionals, this work validates that selection intensity on performance traits has inadvertently concentrated beneficial alleles across multiple breeds, though the high homozygosity evident in some populations warrants consideration of genetic diversity in future licensing decisions.
Read the full abstract on PubMed
Practical Takeaways
- •Understanding genomic selection signatures in warmblood breeds can help breeders identify genetic markers associated with athletic traits and inform future selective breeding decisions.
- •The high homozygosity in Trakehner horses may influence genetic diversity and disease susceptibility; breeders should consider genetic screening and outcrossing strategies to maintain population health.
- •Selection for performance traits (muscle, metabolism, fertility) has shaped breed genomes differently; breeders should be aware these traits are genetically linked and breeding for one may inadvertently affect others.
Key Findings
- •Selection signatures identified on chromosomes 1, 4, and 7 shared across all four German warmblood breeds, suggesting common breeding targets for athletic performance.
- •Trakehner breed showed highest number of runs of homozygosity (ROH), reflecting historical population bottleneck despite modern breeding diversity.
- •Genes affecting muscle functionality (TPM1, TMOD2-3, MYO5A, MYO5C), energy metabolism (AEBP1, RALGAPA2, IGFBP1, IGFBP3-4), and fertility (THEGL, ZPBP1-2, TEX14, ZP1, SUN3, CFAP61) identified as targets of positive selection across breeds.
- •Breed-specific selection signatures detected between Holsteiner, Hanoverian, and Oldenburger breeds despite similar modern breeding goals, reflecting divergent historical breeding policies and crossbreeding practices.