A surprising relative is found in the closet of the Finnhorse

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An 8-year-old Finnhorse mare is presented at the trot. She was sired by a trotter-section stallion. Photo: CC BY-SA 3.0 via Wikimedia Commons

A versatile Finnish horse breed founded more than 110 years ago has surprising genetic links to the Przewalski’s horse, scientists have discovered.

If this finding is confirmed in further genetic sequencing, it may reveal a surprising twist in the domestication of the horse, Laura Kvist and her colleagues reported in the journal Genetics Selection Evolution.

The study team focused on the Finnhorse, a versatile breed divided into four sections: trotters, pony-sized horses, draught horses, and riding horses.

Since its studbook was founded in 1907, the breed has experienced strong selection, particularly for size and colour, with severe population bottlenecks dating back to the initial foundation population.

The breed has also been affected by changes in agricultural and forestry practices.

For their research, Kvist, together with Markku Niskanen, Kristiina Mannermaa, Saskia Wutke and Jouni Aspi, undertook genetic testing of mitochondrial DNA – the maternal line – from 743 Finnhorses to estimate the genetic diversity within the breed.

They found a high level of mitochondrial genetic variation within the breed, despite small population sizes. Nevertheless, inbreeding in Finnhorses was lower than in many other horse breeds.

The scientists identified 16 of the 18 haplogroups described in present-day horses. A haplogroup is a genetic population group that share a common ancestor.

The only ones missing were European haplogroup K and the Middle Eastern haplogroup O.

However, the results delivered one intriguing finding.

“Interestingly,” they reported, “one of these detected haplogroups was previously reported only in the Przewalski’s horse.

A Finnhorse stallion, Turon Myrsky, at the age of 6 years, in the trotter section. Photo: Johanna Rautio CC BY-SA 3.0 via Wikipedia

“The existence of the Przewalski haplogroup F in the Finnhorse, if verified by sequencing whole mitogenomes, may reveal surprising events in the domestication history of the horse.”

This haplogroup was present in four of the Finnhorses analysed for the study, of which three were not included in any of the breeding sections and one was registered as a riding horse.

“To date, haplogroup F has not been found in any modern horse breed, which is unexpected since it was recently suggested that the Przewalski’s horse, the only extant wild horse species, is derived from the early domestic horses of the Botai culture.

“This result contradicted the findings of previous studies that have placed the Przewalski’s horse as a sister taxon of domestic horses, with some possible gene flow from the domestic horse to the Przewalski’s horse.

“This observation opens up new avenues for the study of the domestication of the horse,” they said.

It also supports previous suggestions of a close relationship between the Finnhorse and eastern primitive breeds.

The Finnhorse is closely related to the native Scandinavian, Estonian and Mongolian horses, and presumably to the Russian heavy Mezen horse and the native Lithuanian Žemaitukas horse.

In their study, the researchers also found that Finnhorses cluster with the native Estonian horse and with the native British and Irish breeds.

Kvist, Niskanen and Aspi are with the University of Oulu; Mannermaa is with the University of Helsinki; and Wutke is with the University of Eastern Finland.

Genetic variability and history of a native Finnish horse breed
Laura Kvist, Markku Niskanen, Kristiina Mannermaa, Saskia Wutke and Jouni Aspi
Genetics Selection Evolution 2019 51:35 https://doi.org/10.1186/s12711-019-0480-8

The study, published under a Creative Commons License, can be read here

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