The Estonian Native Horse may harbor genetic “jewels” lost in many of the highly managed horse breeds, according to researchers.
The breed is a medium-size pony found mainly in the western islands of Estonia. It is well-adapted to the harsh northern climate and poor pastures.
The ancestry of the breed has long been debated, including claims it is directly descended from the extinct Tarpan.
Caitlin Castaneda and her colleagues, writing in the journal Genes, note that archaeological findings indicate wild horses inhabited the area of present-day Estonia as early as 10,000 years ago, but went extinct and did not contribute to horse domestication.
Instead, horses domesticated elsewhere arrived in Estonia with human migration from the East during the Late Iron Age/Early Bronze Age, about 3000 years ago.
“The geographic location of Estonia between Eastern and Western powers and its turbulent political history of being conquered and ruled by many has also shaped horse populations,” they said.
However, despite its long cultural history, overall popularity and endangered status, little is known about the breed’s genetic makeup and origin.
A few layman articles have documented the rich variety of coat color patterns within the breed, which is a clear indication of genetic diversity, the authors noted.
To learn more about the breed’s origins, the international team of researchers carried out a population-based genetic study.
The study encompassed 2890 horses of 61 breeds, including 33 Estonian Native Horses.
They found that the breed’s genetic diversity was high when compared to 52 global breeds, and was highest among the eight related Northern European ponies.
The genetically closest breed was found to be the Finn Horse, and the geographically more distant primitive Hucul and Konik. The Finn Horse link was not surprising, given that 13 Finn Horse stallions were used to improve the breed for 15 years when purposeful pure breeding of the Estonian Native Horse began in 1921.
The study team found that maternal lines within the breed were diverse and related to draught and Pontic-Caspian breeds.
The male lines related to draught breeds, and to a unique haplogroup not described before.
None of the 33 Estonian Native Horses tested carried the DMRT3 “gait” mutation.
The authors described the Estonian Native Horse as a genetically distinct and diverse breed of ancient origin with no notable pressure of selective breeding.
This, they said, was illustrated by the highest genetic diversity among the eight genetically closest Northern European pony breeds, the presence of the unique male-related haplotype, and shared gene pools with primitive Eastern European horses such as the Hucul and Konik.
“These findings, along with the knowledge that the breed has been managed semi-ferally with limited human interference, suggest that the genome of the Estonian Native Horse has been shaped predominantly by natural selection and may harbor genetic ‘jewels’ lost in most high-maintenance domestic horse breeds.
The breed, they said, requires more comprehensive analysis through whole genome sequencing to identify signatures of natural and human selection and sequence variants which underlie the breed’s adaptive capabilities.
Special attention should be paid to genetic features that may be related to the breed’s renowned disease resistance and excellent adaptation to the harsh northern climate and nutritionally poor pastures.
“Small, local horse populations like the Estonian Native Horse are potential sources of unique alleles lost in commercial breeds, and appropriate conservation and breed maintenance strategies remain important to prevent further genetic erosion of this unique ancestral legacy.”
The full study team comprised Castaneda, Rytis Juras, Anas Khanshour, Ingrid Randlaht, Barbara Wallner, Doris Rigler, Gabriella Lindgren, Terje Raudsepp and Gus Cothran.
Castaneda, Juras, Raudsepp and Cothran are with Texas A&M University; Khanshour is with the Texas Scottish Rite Hospital for Children; Randlaht is with the Estonian Native Horse Conservation Society; Wallner and Rigler are with the University of Veterinary Medicine Vienna; and Lindgren is with the Swedish University of Agricultural Sciences.
Population Genetic Analysis of the Estonian Native Horse Suggests Diverse and Distinct Genetics, Ancient Origin and Contribution from Unique Patrilines
by Caitlin Castaneda, Rytis Juras, Anas Khanshour, Ingrid Randlaht, Barbara Wallner, Doris Rigler, Gabriella Lindgren, Terje Raudsepp, E. Gus Cothran.
Genes 2019, 10(8), 629; https://doi.org/10.3390/genes10080629