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5 June 2017

Study Reveals Rapid Adaptation of Yakutian Horses to Extreme Cold of the Arctic

Yakutia, located in the Siberian Far East and formally known as the Sahka Republic of the Russian Federation, has long been home to some particularly hardy horses. The Yakutian breed has developed numerous adaptations to help it cope with the extreme cold regularly experienced in the area, such as compact body conformations, extremely hairy winter coats, and acute seasonal differences in metabolic activities. These adaptations combine to allow the breed to live outside all year round in a region where temperatures can drop below -70°C during the coldest winters.

Img: Maarten Takens
Given how the breed has adapted so fittingly to its environment, you would expect that they are likely the descendants of the same horses which have been present in the region since the Pleistocene age; their long history giving them the necessary time to evolve to suit their surroundings. However, new research conducted by a team from the University of Copenhagen has revealed that the modern Yakutian horse was most likely introduced to the area sometime between the 13th and 15th centuries, around the same time as the migration of the Yakut people. This would make them one of the fastest known cases of adaptation to extreme Arctic environments, and certainly worthy of further study.

The multinational study involved the sequencing of the full genomes of 9 present-day Yakutian horses along with that of 2 ancient specimens, one dating back to the 19th century and the other from approximately 5,200 years ago. These were then compared with the genomes of 2 Late Pleistocene horses, 27 modern domesticated horses, and 3 wild Przewalski’s horses.

Somewhat surprisingly, the researchers found that “contemporary Yakutian horses do not descend from the native horses that populated the region until the mid-Holocene, but were most likely introduced following the migration of the Yakut people a few centuries ago.

“Thus, they represent one of the fastest cases of adaptation to the extreme temperatures of the Arctic.”

They further state that as a result of a limited standing variation within gene bodies when the Yakutian horse population was founded, they believe this rapid adaptation to be predominantly a result of cis-regulatory mutations (those which affect regions of non-coding DNA which regulate the transcription of nearby genes and thereby influence the development of anatomy) rather than nonsynonymous changes (nucleotide mutations to the amino acid sequence of a protein which result in biological changes and are subject to natural selection).

They also found evidence that the genes which adapted to allow the Yakutian horse to cope with the region’s harsh winters are the same as those affected in human and mammoth populations when adjusting to extreme cold. This evidence of convergent evolution suggests that “only a few evolutionary strategies are compatible with survival in extremely cold environments.”

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.