Abstract
BackgroundA growing demand for improved physical skills and mental attitude in modern sport horses has led to strong selection for performance in many warmblood studbooks. The aim of this study was to detect genomic regions with low diversity, and therefore potentially under selection, in Swedish Warmblood horses (SWB) by analysing high-density SNP data. To investigate if such signatures could be the result of selection for equestrian sport performance, we compared our SWB SNP data with those from Exmoor ponies, a horse breed not selected for sport performance traits.ResultsThe genomic scan for homozygous regions identified long runs of homozygosity (ROH) shared by more than 85% of the genotyped SWB individuals. Such ROH were located on ECA4, ECA6, ECA7, ECA10 and ECA17. Long ROH were instead distributed evenly across the genome of Exmoor ponies in 77% of the chromosomes. Two population differentiation tests (FST and XP-EHH) revealed signatures of selection on ECA1, ECA4, and ECA6 in SWB horses.ConclusionsGenes related to behaviour, physical abilities and fertility, appear to be targets of selection in the SWB breed. This study provides a genome-wide map of selection signatures in SWB horses, and ground for further functional studies to unravel the biological mechanisms behind complex traits in horses.
Highlights
A growing demand for improved physical skills and mental attitude in modern sport horses has led to strong selection for performance in many warmblood studbooks
The estimated inbreeding coefficient based on loss of heterozygosity in the 380 Swedish Warmblood horses (SWB) ranged from − 0.134 to 0.098 with an average value of 0.006
129 Exmoor ponies and six SWB horses were excluded from further analyses as their fi exceeded the threshold of 5% set in this study
Summary
A growing demand for improved physical skills and mental attitude in modern sport horses has led to strong selection for performance in many warmblood studbooks. The aim of this study was to detect genomic regions with low diversity, and potentially under selection, in Swedish Warmblood horses (SWB) by analysing high-density SNP data. To investigate if such signatures could be the result of selection for equestrian sport performance, we compared our SWB SNP data with those from Exmoor ponies, a horse breed not selected for sport performance traits. The Swedish Warmblood (SWB) is a modern horse breed selected for equestrian sport purposes, mainly show jumping and dressage [1]. Since the demand for physical and mental abilities in sport horses has increased noticeably in the last decades, emphasised selection of SWB horses for specific disciplines, which are dressage or showjumping, is common practice. Genomic regions with loci responsible for body size, milk yield and fertility were detected by ROH analysis in cattle [4,5,6], whereas regions
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