In the 19th century, the planet’s last real wild horses, also called Przewalski’s horses, roamed in the Oriental steppes of China and Mongolia. But at the middle of the 1900’s, these wild horse populations were no longer running free. Just one of the herds survived, originating from a number of wild animals and perhaps only a dozen trained horses. Due to significant preservation initiatives, the existing herds of Przewalski’s horses have now over 2,000 animals, with about 1/4 living in the reintroduction supplies.
Now, scientists have sequenced complete genomes from 10 Przewalski’s horses, with all the originating lineages and other samples taken from various museums going back more than 100 years, and then compared these samples to the genomes extracted from 30 domesticated horses to offer a specific look at this vulnerable species’ biological structure, with both its past and existing members.
The uniqueness of this idea is to have not just taken the current-day genomic variety of Przewalski’s equines, but also to observe their previous genomic variety, utilizing old museum samples. That way they can evaluate the inherited impact of over a century of captivity on what has been a seriously endangered species.
This genomic proof helps to fix an ongoing issue in equine evolution, related to the connections the wild and domesticated horses. The ancestors of these wonderful animals and domesticated individuals remained linked by their gene background for a lengthy period after their separation, produced more than 45,000 years ago, as the scientists report. Their communities continued to have their members reproducing between themselves even after people began to domesticate the animals over 5,000 years ago.
The experts have also shown that at the very beginning in captivity, some time during the 19th century, domesticated animals contributed a lot to the biological lineages of the Przewalski’s horses. This study indicates that not all current Przewalski’s lineages are equally found in their gene pool.
The experts discovered the biggest inherited variations between wild and domesticated equines in traits involved in metabolic rate, heart problems, muscle shrinkage, breeding, actions and signaling routes.
The results also prove that the last century of captivity has left serious marks on many Przewalski’s horses, generating lower genetic variety, advanced inbreeding and, in a few situations, the introduction of domesticated horse genes among the wild herds. In the most severe cases, about one fourth of the gene pool of Przewalski’s horses contains genetic versions obtained from their domesticated counterparts.
Even if Przewalski’s horses got through an excessive population problem, the horses seem to return to a better situation, and are still genetically different from the rest of the equine species. Now there is hope for other vulnerable animal populations, battling with similar issues.
The results also are proof of the significance of historical DNA traits in knowing more about domestication. The scientists say that they want to evaluate a lot more ancient species, both domestic and wild, in order to compare them over time. This research has the main objective of rebuilding the lineage of horses over millennia of domestication.
Image source: Equitrekking