Rare, Przewalski's Horse's Genetics Reveal More about the World's Last Wild Horses

First Posted: Sep 25, 2015 06:35 AM EDT

In the 1870s, the world's last truly wild horses lived in the Asian steppes of Mongolia and china. But in the 1960s, these wild horses were no longer free, and only one captive population remained due to conservation efforts. Now, though, scientists are taking a closer look at Przewalski's horses to better understand their history.

In this latest study, the scientists sequenced the complete genomes of 11 Przewalski's horses, including the founding lineages and five historical museum specimens dating back more than a century. Then, the researchers compared these genomes to the genomes of the 28 domesticated horses to provide them a detailed look at the endangered animals.

"The novelty of our approach is to have not only surveyed the present-day genomic diversity of Przewalski's horses, but also to monitor their past genomic diversity, leveraging on museum specimens," said Ludovic Orlando, one of the researchers, in a news release. "That way we could assess the genetic impact of more than 100 years of captivity in what used to be a critically endangered animal."

In fact, the new genomic evidence helped solve a long-standing debate in horse evolution about the relationships between wild and domestic horses. The scientists found that the ancestors of Przewalski's horses and domesticated horses remained connected by gene flow for a long time after their divergence about 45,000 years ago. Their populations continued to mix even after humans started to domesticate the horse about 5,500 years ago.

In addition, 110 years of captivity have left a mark on the Przewalski's horses, in the form of lower genetic diversity, increased inbreeding and, in some cases, the significant introduction of genes from domesticated individuals.

"Even though Przewalski's horses went through an extreme demographic collapse, the population seems to recover and is still genetically diverse," said Orlando. "There is, thus, hope for [other] endangered populations, fighting similar demographic issues."

The findings are published in the journal Current Biology.

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