A study involving Arabian horses from 12 countries found that some populations maintained a larger degree of genetic diversity and that the breed did not contribute genetically to the modern-day Thoroughbred, contrary to popular thought.
An international team of scientists was led by the University of Florida’s Samantha Brooks, a UF/IFAS assistant professor of animal sciences; Cornell University’s Doug Antczak, the Dorothy Havemeyer McConville Professor of Equine Medicine at the Baker Institute for Animal Health; and Andy Clark, the Jacob Gould Schurman Professor in Cornell’s department of molecular biology and genetics.
The group collected and examined DNA samples from 378 Arabian horses from Qatar, Iran, UAE, Poland, USA, Egypt, Jordan, Kuwait, United Kingdom, Australia, Denmark and Canada. The research, published June 16 in the journal Scientific Reports, was conducted over an 8-year period.
Brooks contrasted the discovery of more diverse populations with the samples they received from racing Arabians. Another longstanding myth says that the Arabian contributed genetically to the modern Thoroughbred, but the racing Arabians’ DNA told a different story.
“What we found was that in the area where this breed originates—likely the near East region, but we don’t know exactly—there’s a healthy level of diversity.”
The horse is prized for characteristics like heat tolerance and endurance, as well as its unique appearance, with a dish-shaped facial profile, wide-set eyes, an arched neck and a high tail carriage. It has been exported from its ancestral homeland for centuries, with some modern lineages drawn strictly from these smaller genetic pools, giving the breed a reputation for inbred disorders. While this was true for some groups they tested, Brooks noted, they also found remarkable diversity when considering the breed as a whole.
“What we found in these samples was not that much Arabian ancestry was part of the Thoroughbred line, but the opposite: that Thoroughbred DNA exists in most of the modern racing Arabian lines, indicating a more recent interbreeding within this group,” Brooks said. “I can’t speculate on the how or why, but this is clearly the story the DNA is telling us.”
New research adds to the strong evidence that the Akhal-Teke, not the Arabian, is the breed of foundation stallions of the modern Thoroughbred.
“Contrary to popular belief, we could detect no significant genomic contribution of the Arabian breed to the Thoroughbred racehorse, including Y chromosome ancestry.”
“Recently… an analysis of horse Y chromosome haplotypes has indicated that the Y haplotype of the “Darley Arabian” actually originated from the Turkoman[/Akhal-Teke] horse, an ancient breed from the Middle East and Central Asia that is… also an “Oriental” type breed.”
“Five of the race-use [Arabian] horses carried the Tb-oB1* haplogroup attributed to the “Byerley Turk” foundation sire of the Thoroughbred breed. Tb-oB1* is found within a variety of breeds and lineages, including the Turkomen[/Akhal-Teke]. Therefore, these five horses may carry Y chromosomes derived from ancestors common to both racing Arabians and the Thoroughbred breed.” – exctracts from phys.org and nature.com.