Wild horse
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| Equus ferus Boddaert, 1785 |
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The Wild Horse (Equus ferus) is a member of the Horse genus and was found in Europe and Asia. The true wild horse is not merely a feral horse like the Mustang; a true wild horse species is one that was never successfully domesticated.
Two species or subspecies (taxonomy is debated) of wild horses survived into modern times: The Tarpan or Eurasian Wild Horse (Equus ferus ferus), and the Przewalski's Horse or Mongolian Wild Horse (classification disputed, either Equus ferus przewalskii or Equus przewalskii). The Tarpan became extinct in 1875. The Przewalski's Horse is still found today, though it is an endangered species and for a time was considered extinct in the wild. Roughly 1500 animals are protected in zoos around the world, and today, a small breeding population has been reintroduced in Mongolia.[1] As of 2005, a cooperative venture between the Zoological Society of London and Mongolian Scientists has resulted in a free-ranging population of 248 animals in the wild.[2]
The Przewalski has notable biological differences from the domestic horse: unlike domesticated horses, which have 64 chromosomes, the wild horse has 66 chromosomes. However, the offspring of Przewalski and domestic horses are fertile, possessing 65 chromosomes.[3]
Other species of wild horses were once indigenous to North America, populating the continent before and during the Ice Age. Approximately 10,000 years ago, horses in the Western Hemisphere migrated to Eurasia across the Bering land bridge, and fanned out from Siberia to the rest of Asia, Europe, and the Middle East. What horses remained behind became extinct in North America. There are two competing theories about why this happened. One theory holds that climate changes associated with the end of the last Ice Age caused the extinction of the horse, the mammoth and other large land animals. Another theory holds that newly-arrived humans hunted horses to extinction. It is also possible that it was a combination of both factors.[4]
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[edit] Taxonomy
While taxonomy is debated, one view is that the wild horse and domestic horse belong to the same species. Thus, to conform to the Code of the International Commission of Zoological Nomenclature the scientific name of the wild horse Equus ferus was discontinued by Wilson and Reeder in 1993 and wild horses were added to Equus caballus, the name given by Linnaeus. Some scientists criticized this change of the scientific name, arguing in favor of a distinction between wild and feral or domesticated animals.[5]
As a result, in 2003, the International Commission on Zoological Nomenclature "conserved the usage of 17 specific names based on wild species, which are pre-dated by or contemporary with those based on domestic forms", re-confirming Equus ferus for the wild horse. Taxonomists who consider the domestic horse a subspecies of the wild horse should use Equus ferus caballus but the name Equus caballus remains available for the domestic horse where it is considered to be a separate species. [6]
[edit] Feral horses
When Europeans reintroduced the horse to the Americas, beginning with the arrival of the Conquistadors in the 15th century, some horses escaped and formed feral herds known today as Mustangs. The Australian equivalent to the mustang is the brumby, descendants of the horses let loose in Australia by English settlers. In Spain, the free-ranging feral horse is known as Sorraia. There are also isolated populations of feral horses in a number of places, including Sable Island off the coast of Nova Scotia, and Assateague Island off the coast of Virginia. Some of these horses are the descendants of horses who managed to swim to land when they were shipwrecked. While these are often referred to as "wild" horses, they are the descendants of domesticated ancestors and not truly "wild" in the biological sense of having no domesticated ancestors.
[edit] References
- ^ "Przewalski's Horse," Smithsonian National Zoological Park, accessed June 25, 2006
- ^ "An extraordinary return from the brink of extinction for worlds last wild horse" ZSL Living Conservation, December 19, 2005.
- ^ The American Museum of Natural History When Is a Wild Horse Actually a Feral Horse?
- ^ "Ice Age Horses May Have Been Killed Off by Humans" National Geographic News, May 1, 2006.
- ^ Van Vuure, C. 2005. Retracing the Aurochs: History, Morphology and Ecology of an Extinct Wild Ox. Pensoft Publishers. Sofia-Moscow.
- ^ International Commission on Zoological Nomenclature. 2003. Opinion 2027 (Case 3010). Usage of 17 specific names based on wild species which are pre-dated by or contemporary with those based on domestic animals (Lepidoptera, Osteichthyes, Mammalia): conserved. Bull.Zool.Nomencl., 60:81-84.
- Equid Specialist Group 1996. Equus ferus. In: IUCN 2006. 2006 IUCN Red List of Threatened Species. <www.iucnredlist.org>. Downloaded on 22 May 2006 from http://www.iucnredlist.org/search/details.php?species=41763.
- Moelman, P.D. 2002. Equids. Zebras, Assess and Horses. Status Survey and Conservation Action Plan. IUCN/SSC Equid Specialist Group. IUCN, Gland, Switzerland. (http://www.iucn.org/themes/ssc/publications/actionplans.htm#Equids2002)
