The Arabian horse, one of the world's oldest breeds of any domesticated animal, is characterized by natural beauty, graceful movement, athletic endurance, and, as a result of its development in the arid Middle East, the ability to thrive in a hot, dry environment. Here we studied 378 Arabian horses from 12 countries using equine single nucleotide polymorphism (SNP) arrays and whole-genome re-sequencing to examine hypotheses about genomic diversity, population structure, and the relationship of the Arabian to other horse breeds. We identified a high degree of genetic variation and complex ancestry in Arabian horses from the Middle East region. Also, contrary to popular belief, we could detect no significant genomic contribution of the Arabian breed to the Thoroughbred racehorse, including Y chromosome ancestry. However, we found strong evidence for recent interbreeding of Thoroughbreds with Arabians used for flat-racing competitions. Genetic signatures suggestive of selective sweeps across the Arabian breed contain candidate genes for combating oxidative damage during exercise, and within the "Straight Egyptian" subgroup, for facial morphology. Overall, our data support an origin of the Arabian horse in the Middle East, no evidence for reduced global genetic diversity across the breed, and unique genetic adaptations for both physiology and conformation.
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This study was made possible by National Priorities Research Program (NPRP) grant 6-1303-4-023 from the Qatar National Research Fund (a member of Qatar Foundation). Support was also received from The Harry M. Zweig Memorial Fund for Equine Research, Arabian Horse Foundation, Animal Health Foundation, Dorothy Russell Havemeyer Foundation, Inc. (DFA), and a Meinig Family Investigator award (AGC).
The genotype data generated during this study are available at Mendeley Data: https://doi.org/10.17632/mkk5khxrbp.3. All raw sequencing data generated in this study has been submitted to the ENA under study #PRJEB33818.
Cosgrove, Elissa J.; Sadeghi, Raheleh; Schlamp, Florencia; Holl, Heather M.; Moradi-Shahrbabak, Mohammad; Miraei-Ashtiani, Seyed Reza; Abdalla, Salma; Shykind, Ben; Troedsson, Mats H. T.; Stefaniuk-Szmukier, Monika; Prabhu, Anil; Bucca, Stefania; Bugno-Poniewierska, Monika; Wallner, Barbara; Malek, Joel; Miller, Donald C.; Clark, Andrew G.; Antczak, Douglas F.; and Brooks, Samantha A., "Genome Diversity and the Origin of the Arabian Horse" (2020). Veterinary Science Faculty Publications. 50.