A horse’s gait, an attribute central to the animal’s importance to humans, is influenced by a genetic mutation that was spread by humans across the world, research has shown.
The research team, led by Dr Leif Andersson from the Swedish University of Agricultural Sciences, explored the distribution of a mutation in the DMRT3 gene which has a clear influence on movement in the gaited breeds. It is known as the “gait keeper” gene.
“All over the world, horses have been used for everyday transportation, in military settings, cattle herding and agricultural power, pulling carriages and carts, pleasure riding or racing,” Dr Andersson said.
“Over the centuries, horse populations and breeds have been shaped by humans based on the different purposes for which the animals were used.”
The DMRT3 gene is central to the utility of horses to humans, as it controls a range of gaits as well as pace. From racing to pleasure riding, many species have been bred to encourage smoothness of gait.
“For example, the Paso Fino is a breed from Latin America in which the frequency of the ‘gait keeper’ mutation is nearly 100 percent,” Andersson said.
“It is claimed that the Paso Fino gait is so smooth that you can have a glass of wine in your hand without letting it spill,” Andersson said.
Gaited breeds occurred around the globe, indicating that such gaitedness was an old trait, selected for in many breeds.
The team analyzed 4396 horses from 141 breeds around the world and found that the ‘gait keeper’ mutation is spread across Eurasia from Japan in the East, to the British Isles in the West, on Iceland, in both South and North America, and also in breeds from South Africa.
The researchers found that the DMRT3 mutation was present in 68 of the 141 genotyped horse breeds at a frequency ranging from 1 percent to 100 per cent, distributed worldwide.
Breeds with a high frequency of the mutation – greater than 50 percent – are either classified as gaited or bred for harness racing.
“Humans have spread this mutation across the world primarily because horses carrying this mutation are able to provide a very smooth ride, in some breeds referred to as a running walk,” Dr Andersson said.
“During such ambling gaits the horse has at least one foot on the ground that means that the vertical movement of the rider is minimal.”
The findings of the research, entitled “Worldwide frequency distribution of the ‘Gait keeper’ mutation in the DMRT3 gene”, have been published in the journal, Animal Genetics.
Andersson and his colleagues said that, for centuries, domestic horses represented an important means of transport and served as working and companion animals.
Although their role in transportation is less important today, many horse breeds are still subject to intense selection based on their pattern of locomotion.
A striking example of such a selected trait, they said, was the ability of a horse to perform additional gaits other than the common walk, trot and gallop. Those could be four-beat ambling gaits, which are particularly smooth and comfortable for the rider, or pacing, used mainly in racing.
Promerová, M., Andersson, L. S., Juras, R., Penedo, M. C. T., Reissmann, M., Tozaki, T., Bellone, R., Dunner, S., Hořín, P., Imsland, F., Imsland, P., Mikko, S., Modrý, D., Roed, K. H., Schwochow, D., Vega-Pla, J. L., Mehrabani-Yeganeh, H., Yousefi-Mashouf, N., G. Cothran, E., Lindgren, G. and Andersson, L. (2014), Worldwide frequency distribution of the ‘Gait keeper’ mutation in the DMRT3 gene. Animal Genetics. doi: 10.1111/age.12120
The full study can be read online here.