Old surviving horse samples a boon for genetic researchers

Examples of materials sampled for the study. Image: Kvist et al. https://doi.org/10.1111/age.13256

Old horse mementos in private collections may not be worth their weight in gold, but they are certainly worth their weight in DNA.

A study published this week in the journal Animal Genetics highlights the value of old horse samples in tracing lineages within horse breeds.

Researchers Laura Kvist, Johanna Honka, Daniela Salazar, Tuija Kirkinen and Karin Hemmann used historical DNA samples to examine the history of the Finnhorse, which is native to Finland.

“The early stages of the formation of breeds have, to our knowledge, never been studied using DNA samples originating from those times,” they said.

The Finnhorse is a versatile breed that has remained essentially the same since the 18th century, but the size has increased and the color spectrum has decreased during the 20th century.

In their study, they collected historical hair, tooth, bone, and hoof samples of horses from the end of the 19th century and throughout the 20th century, originating from private collections, museums, schools, and excavations, in order to examine the history of the breed.

A total of 416 samples were processed for DNA extraction, of which 325 were hair and 91 were tooth, bone, or hoof.

They sequenced a fragment of mitochondrial DNA from these samples to study the history and evolution of maternal lineages of horses back to the early days of the breed.

Their findings cast a light on how the genetic diversity of the Finnhorse has changed since the foundation of the breed.

“We observed high maternal haplotype and nucleotide diversity at the time during the foundation of the breed, and a decrease in both measures during 1931–1970,” they reported. “In addition, some haplotypes present in the early stages of the breed were seemingly lost as these were not detected in modern Finnhorses.

“A drop in genetic diversity was accompanied by a reduction of the female effective population size.”

The researchers said their study showed that historical material sourced from museums, private individuals, and archaeological excavations is valuable for examining domestic animal breeds’ history.

“Instead of examining modern DNA, this type of material provides a tool to follow the development of breeds as it happens, using a time series of historical samples.

“With historical DNA, we followed the evolution of maternal lineages and could detect, for example, loss of maternal lineages, and changes in female effective population size and genetic diversity.”

Kvist, Honka, Salazar are with the University of Oulu; while Tuija Kirkinen and Karin Hemmann are with the University of Helsinki.

Kvist, L., Honka, J., Salazar, D., Kirkinen, T. & Hemmann, K. (2022) Memories, museum artefacts and excavations in resolving the history of maternal lineages in the Finnhorse. Animal Genetics, 00, 1– 8. Available from: https://doi.org/10.1111/age.13256

The study, published under a Creative Commons Licensecan be read here.

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