In the 1870s, the world's last truly wild horses, known as Przewalski's horses, lived in the Asian steppes of Mongolia and China. Przewalski's horses became extinct in the wild in the 1960s, but survived in captivity, thanks to major conservation efforts. The current population is still endangered, with just 2,109 individuals, one-quarter of which live in Chinese and Mongolian reintroduction reserves. These horses descend from a founding population of 12 wild-caught Przewalski's horses and possibly up to four domesticated individuals. Now, researchers, reporting online in the Cell Press journal Current Biology on September 24, 2015, have sequenced the complete genomes of eleven Przewalski's horses, including all of the founding lineages and five historical, museum specimens dating back more than a century, and compared them to the genomes of 28 domesticated horses to provide a detailed look at the endangered animals, both past and present. The Current Biology article is titled “"Evolutionary Genomics and Conservation of the Endangered Przewalski's Horse.” "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," says Dr. Ludovic Orlando of the University of Copenhagen's Natural History Museum of Denmark. "That way we could assess the genetic impact of more than 100 years of captivity in what used to be a critically endangered animal." The genomic evidence helps to solve a long-standing debate in horse evolution, regarding the relationships between wild and domestic horses. The ancestors of Przewalski's horses and domesticated horses remained connected by gene flow for a long time after their divergence, some 45,000 years ago, the researchers report.
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