Przewalski's horse
Przewalski's horse | |
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Przewalski's horse | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Perissodactyla |
Family: | Equidae |
Genus: | Equus |
Species: | |
Subspecies: | E. f. przewalskii
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Trinomial name | |
Equus ferus przewalskii (I. S. Polyakov, 1881)
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Przewalski's horse range (reintroduced; missing distribution in Russia, Belarus, and Ukraine) | |
Synonyms | |
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Przewalski's horse (
Several genetic characteristics of Przewalski's horse differ from what is seen in modern domestic horses, indicating neither is an ancestor of the other. For example, the Przewalski has 33 chromosome pairs, compared to 32 for the domestic horse. Their ancestral lineages split from a common ancestor between 38,000 and 160,000 years ago, long before the
The Przewalski's horse is stockily built, smaller, and shorter than its domesticated relatives. Typical height is about 12–14 hands (48–56 inches, 122–142 cm), and the average weight is around 300 kg (660 lb). They have a dun coat with pangaré features and often have dark primitive markings.
Taxonomy
Przewalski's horse was formally described as a novel species in 1881 by Ivan Semyonovich Polyakov. The taxonomic position of Przewalski's horse remains controversial, and no consensus exists whether it is a full species (as Equus przewalskii); a subspecies of Equus ferus the wild horse, (as Equus ferus przewalskii in trinomial nomenclature, along with two other subspecies, the domestic horse E. f. caballus, and the extinct tarpan E. f. ferus), or even a subpopulation of the domestic horse.[6][7][8] The American Society of Mammalogists considers the Przewalski's horse and the tarpan to both be subspecies of Equus ferus, and classifies the domestic horse as separate species, Equus caballus.[9]
Lineage
Early sequencing studies of DNA revealed several genetic characteristics of Przewalski's horse that differ from what is seen in modern domestic horses, indicating neither is ancestor of the other, and supporting the status of Przewalski horses as a remnant wild population not derived from modern domestic horses.[10] The evolutionary divergence of the two populations was estimated to have occurred about 45,000 YBP,[11][12] while the archaeological record places the first horse domestication about 5,500 YBP by the ancient central-Asian Botai culture.[11][13] The two lineages thus split well before domestication, most likely due to climate, topography, or other environmental changes.[11]
Several subsequent DNA studies produced partially contradictory results. A 2009 molecular analysis using ancient DNA recovered from archaeological sites placed Przewalski's horse in the middle of the domesticated horses.[8] However, a 2011 mitochondrial DNA analysis suggested that Przewalski's and modern domestic horses diverged some 160,000 years ago.[14] An analysis based on whole genome sequencing and calibration with DNA from old horse bones gave a divergence date of 38,000–72,000 years ago.[15]
In 2018, a new analysis involved genomic sequencing of ancient DNA from horse remains associated with the mid-fourth-millennium BCE Botai culture and bearing marks considered characteristic of domestication, as well as domestic horses from more recent archaeological sites, for comparison with those of modern domestic and Przewalski's horses. The study revealed that the Botai horses were members of the Przewalski's horse lineage, rather than that of modern domestic horses as was previously believed. Further, all of the modern Przewalski's horses analyzed were found to nest within the
In any case, the Botai horses were found to have negligible genetic contribution to any of the ancient or modern domestic horses studied, indicating that the domestication of the latter was independent, involving a different wild population, from any possible domestication of Przewalski's horse by the Botai culture.[16][17][18]

Characteristics
Przewalski's horse is stockily built in comparison to domesticated horses, with shorter legs, though being much smaller and shorter than its domesticated relatives. Typical height is about 12–14 hands (48–56 inches, 122–142 cm), and length is about 2.1 m (6 ft 11 in). It weighs around 300 kilograms (660 lb). The coat is generally dun in color with pangaré features, varying from dark brown around the mane, to pale brown on the flanks, and yellowish-white on the belly, as well as around the muzzle. The legs of Przewalski's horse are often faintly striped, also typical of primitive markings.[20] The mane stands erect and does not extend as far forward,[21] while the tail is about 90 cm (35.43 in) long, with a longer dock and shorter hair than seen in domesticated horses. The hooves of Przewalski's horse are longer in the front and have significantly thicker sole horns than feral horses, an adaptation that improves hoof performance on terrain.[22]
Genomics
The karyotype of Przewalski's horse differs from that of the domestic horse, having 33 chromosome pairs versus 32, apparently due to a fission of a large chromosome ancestral to domestic horse chromosome 5 to produce Przewalski's horse chromosomes 23 and 24,[23] though conversely, a Robertsonian translocation that fused two chromosomes ancestral to those seen in Przewalski's horse to produce the single large domestic horse chromosome has also been proposed.[24]
Many smaller
Ecology and behavior

Przewalski reported the horses forming troops of between five and fifteen members, consisting of an old stallion, his mares and foals.[21] Modern reintroduced populations similarly form family groups of one adult stallion, one to three mares, and their common offspring that stay in the family group until they are no longer dependent, usually at two or three years old. Young females join other harems, while bachelor stallions as well as old stallions who have lost their harems join bachelor groups.[25] Family groups can join to form a herd that moves together.[citation needed]
The patterns of their daily lives exhibit horse behavior similar to that of feral horse herds. Stallions herd, drive, and defend all members of their family, while the mares often display leadership in the family. Stallions and mares stay with their preferred partners for years. While behavioral synchronization is high among mares, stallions other than the main harem stallion are generally less stable in this respect.[citation needed]
Home range in the wild is little studied, but estimated as 1.2–24 km2 (0.46–9.3 sq mi) in the Hustai National Park and 150–825 km2 (58–319 sq mi) in the Great Gobi B Strictly Protected Area.[26] The ranges of harems are separated, but slightly overlapping.[25] They have few modern predators, but one of the few is the Himalayan wolf.[27]
Horses maintain visual contact with their family and herd at all times, and have a host of ways to communicate with one another, including vocalizations,
The historical population was said to have lived in the "wildest parts of the desert" with a preference for "especially saline districts".[21] They were observed mostly during spring and summer at natural wells, migrating to them by crossing valleys rather than by way of higher mountains.[29]

Diet
Przewalski horse's diet consists of vegetation. Many plant species are in a typical Przewalski's horse environment, including: Elymus repens, Carex spp., Fabaceae, and Asteraceae.[30] Looking at the species' diet overall, Przewalski's horses most often eat E. repens, Trifolium pratense, Vicia cracca, Poa trivialis, Dactylis glomerata, and Bromus inermis.[30]
While the horses eat a variety of different plant species, they tend to favor different species at different times of year. In the springtime, they favor Elymus repens,
In winter the horses eat
Reproduction
Mating occurs in late spring or early summer. Mating stallions do not start looking for mating partners until the age of five. Stallions assemble groups of mares or challenge the leader of another group for dominance. Females are able to give birth at the age of three and have a gestation period of 11–12 months. Foals are able to stand about an hour after birth.[33] The rate of infant mortality among foals is 25%, with 83.3% of these deaths resulting from leading stallion infanticide.[34] Foals begin grazing within a few weeks but are not weaned for 8–13 months after birth.[33] They reach sexual maturity at two years of age.[35]
Population
History
Przewalski's-type wild horses appear in European cave art dating as far back as 20,000 years ago,[1] but genetic investigation of a 35,870-year-old specimen from one such cave instead showed affinity with extinct Iberian horse lineage and the modern domestic horse, suggesting that it was not Przewalski's horse being depicted in this art.[36] Horse skeletons dating to the fifth to the third millennia BCE, found in Central Asia, with a range extending to the southern Urals and the Altai, belong to the genetic lineage of Przewalski's horse.[37] Of particular note are the horses of this lineage found in the archaeological sites of the Chalcolithic Botai culture. Sites dating from the mid-fourth-millennium BCE show evidence of horse domestication,[38] though their status as domesticated horses has been recently challenged.[19] Analysis of ancient DNA from Botai horse specimens from about 3000 BCE reveal them to have DNA markers consistent with the lineage of modern Przewalski's horses.[16]
There are sporadic reports of Przewalski's horse in the historical record prior to its formal characterization. The Buddhist monk Bodowa wrote a description of what is thought to have been Przewalski's horse about AD 900,
The species is named after a Russian colonel of Polish descent,
After 1903, there were no reports of the wild population until 1947, when several isolated groups were observed and a lone filly captured. Although local herdsmen reported seeing as many as 50 to 100 takhis grazing in small groups at that time, there were only sporadic sightings of single groups of two or three animals thereafter, mostly near natural wells.[29] Two scientific expeditions in 1955 and 1962 failed to find any, and after herders and naturalists reported single harem groups in 1966 and 1967, the last observation of the wild horse in its native habitat was of a single stallion in 1969.[29][40] Expeditions after this failed to locate any horses, and the species would be designated "extinct in the wild" for over 30 years.[29] Competition with livestock, hunting, capture of foals for zoological collections, military activities, and harsh winters recorded in 1945, 1948, and 1956 are considered to be main causes of the decline in Przewalski's horse population.[14]
The wild population was already rare at the time of its first scientific characterization. Przewalski reported seeing them only from a distance and may actually have instead sighted herds of local onager, Mongolian wild asses, and he was only able to obtain the type specimen from Kirghiz hunters.[40] The range of Przewalski's horse was limited to the arid Dzungarian Basin in the Gobi Desert.[21] It has been suggested that this was not their natural habitat, but, like the onager, they were a steppe animal driven to this inhospitable last refuge by the dual pressures of hunting and habitat loss to agricultural grazing.[31] There were two distinct populations recognized by local Mongolians, a lighter steppe variety and a darker mountain one, and this distinction is seen in early twentieth-century descriptions. Their mountainous habitat included the Takhiin Shar Nuruu (The Yellow Wild-Horse Mountain Range).[40] In their last decades in the wild, the remnant population was limited to the small region between the Takhiin Shar Nuruu and Bajtag-Bogdo mountain ridges.[29]

Captivity
Attempts to obtain specimens for exhibit and
The situation was improved when the exchange of breeding animals among facilities increased genetic diversity and there was a consequent improvement in fertility, but the population experienced another genetic bottleneck when many of the horses failed to survive World War II. The most valuable group, in
In 1957, a wild-caught mare captured as a foal a decade earlier was introduced into the Ukrainian captive population. This would prove the last wild-caught horse, and with the presumed extinction of wild population, last sighted in Mongolia in the late 1960s, the captive population became the sole representatives of Przewalski's horse.[29] Genetic diversity received a much needed boost from this new source, with the spread of her bloodline through the inbred captive groups leading to their increased reproductive success, and by 1965 there were more than 130 animals spread among thirty-two zoos and parks.
Conservation efforts

In 1977, the Foundation for the Preservation and Protection of the Przewalski Horse was founded in Rotterdam, the Netherlands, by Jan and Inge Bouman. The foundation started a program of exchange between captive populations in zoos throughout the world to reduce inbreeding, and later began a breeding program of its own. As a result of such efforts, the extant herd has retained a far greater genetic diversity than its genetic bottleneck made likely.[14] By 1979, when this concerted program of population management to maximize genetic diversity was begun, there were almost four hundred horses in sixteen facilities,[29] a number that had grown by the early 1990s to over 1,500.[42]
While dozens of zoos worldwide have Przewalski's horses in small numbers, specialized reserves are also dedicated primarily to the species. The world's largest captive-breeding program for Przewalski's horses is at the
Le Villaret, located in the Cevennes National Park in southern France and run by the Association Takh, is a breeding site for Przewalski's horses that was created to allow the free expression of natural Przewalski's horse behaviors. In 1993, eleven zoo-born horses were brought to Le Villaret. Horses born there are adapted to life in the wild, being free to choose their own mates and required to forage on their own. This was intended to produce individuals capable of being reintroduced into Mongolia. In 2012, 39 individuals were at Le Villaret.[50] An intensely researched population of free-ranging animals was also introduced to the Hortobágy National Park puszta in Hungary; data on social structure, behavior, and diseases gathered from these animals are used to improve the Mongolian conservation effort.[25] An additional breeding population of Przewalski's horses roams the former Döberitzer Heide military proving ground, now a nature reserve in Dallgow-Döberitz, Germany. Established in 2008, this population comprised 24 horses in 2019.[51]

Reintroduction
Reintroductions organized by Western European countries started in the 1990s. These were later stopped, mostly for financial reasons. In 2011, Prague Zoo started a new project, Return of the Wild Horses. With the support of public and many strategic partners, these yearly transports of captive-bred horses into the Great Gobi B Strictly Protected Area continue today.[52] Since 2004, there is also a program to reintroduce Przewalski's horses that were bred in France into Mongolia.[53]
Several populations have now been released into the wild. A cooperative venture between the
In 2001, Przewalski's horses were reintroduced into the Kalamaili Nature Reserve in Xinjiang, China.[34] The Przewalski's Horse Reintroduction Project of China was initiated in 1985 when 11 wild horses were imported from overseas. After more than two decades of effort, the Xinjiang Wild Horse Breeding Centre has bred a large number of the horses, 55 of which were released into the Kalamely Mountain area. The animals quickly adapted to their new environment. In 1988, six foals were born and survived, and by 2001, over 100 horses were at the centre. As of 2013[update], the center hosted 127 horses divided into 13 breeding herds and three bachelor herds.
The first reintroduction into the Orenburg region, on the Russian steppe, occurred in 2016.[55][56] Plans were also announced in 2014 to reintroduce them in central Kazakhstan.[57]
The reintroduced horses successfully reproduced, and the status of the animal was changed from "extinct in the wild" to "endangered" in 2005,[42] while on the IUCN Red List they were reclassified from "extinct in the wild" to "critically endangered" after a reassessment in 2008,[58] and from "critically endangered" to "endangered" after a 2011 reassessment.[54]
Assisted reproduction and cloning

In the earlier decades of captivity, the insular breeding by individual zoos led to inbreeding and reduced fertility. In 1979, several American zoos began a collaborative breeding-exchange program to maximize genetic diversity.[59] Recent advances in equine reproductive science have also been used to preserve and expand the gene pool. Scientists at the Smithsonian Institution's National Zoo successfully reversed a vasectomy on a Przewalski's horse in 2007—the first operation of its kind on this species, and possibly the first ever on any endangered species. While normally a vasectomy may be performed on an endangered animal under limited circumstances, particularly if an individual has already produced many offspring and its genes are overrepresented in the population, scientists realized the animal in question was one of the most genetically valuable Przewalski's horses in the North American breeding program.[60] The first birth by artificial insemination occurred on 27 July 2013 at the Smithsonian Conservation Biology Institute.[61][62]
In 2020, the first cloned Przewalski's horse was born, the result of a collaboration between
The somatic cell donor was a Przewalski's horse stallion named Kuporovic, born in the UK in 1975, and relocated three years later to the US, where he died in 1998. Due to concerns over the loss of
The cloned horse was named Kurt, after Dr. Kurt Benirschke, a geneticist who developed the idea of cryopreserving genetic material from species considered to be endangered. His ideas led to the creation of the Frozen Zoo as a genetic library.[67] Once the foal matures, he will be relocated to the breeding herd at the San Diego Zoo Safari Park,[68] so as to pass Kuporovic's genes into the larger captive Przewalski's horse population and thereby increase the genetic variation of the species.[63]
In 2023, a genetic twin of Kurt was born from cloning with the help of the San Diego Zoo Global Frozen Zoo. It is the first reported case of any endangered species to have more than one clone being successfully produced. This individual will eventually join Kurt and a young female named Holly in San Diego Zoo Safari Park.[69]
See also
- Mongolian horse (domestic)
References
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- ^ Mulvey, Stephen (20 April 2006). "Wildlife defies Chernobyl radiation". BBC News. Retrieved 3 October 2007.
- ^ Gill, Victoria (27 July 2011). "Chernobyl's Przewalski's horses are poached for meat". BBC Nature. Archived from the original on 27 April 2018. Retrieved 2 May 2016.
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Further reading
- Boyd, Lee; Houpt, Katherine A. (1994). Przewalski's Horse: The history and biology of an endangered species. Albany, New York: OCLC 28256312– via Google Books.
- "FC Wales turns clock back thousands of years with 'wild' solution to looking after ancient forest site" (Media release). Forestry Commission, Wales, U.K. 16 September 2004. No: 7001. Archived from the original on 6 July 2006.
- "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. International Commission on Zoological Nomenclature. 60: 81–84. 2003. Opinion 2027 (Case 3010). Archived from the original on 24 February 2006.
- Ishida, Nobushige; et al. (1995). "Mitochondrial DNA sequences of various species of the genus Equus with special reference to the phylogenetic relationship between Przewalskii's wild horse and domestic horse". Journal of Molecular Evolution. 41 (2): 180–188. S2CID 2884878.
- Jansen, Thomas; et al. (2002). "Mitochondrial DNA and the origins of the domestic horse". PMID 12130666.
- King, S. R. B.; Gurnell, J. (2006). "Scent-marking behaviour by stallions: an assessment of function in a reintroduced population of Przewalski horses (Equus ferus przewalskii)". Journal of Zoology. 272 (1): 30–36. .
- van Cleaf, K. (2006). Przewalski's Horses (Print ed.). Edina, MN: ABDO Pub. Co.
- Wakefield, S.; Knowles, J.; Zimmermann, W.; Van Dierendonck, M. (2002). "Status and action plan for the Przewalski's Horse (Equus ferus przewalski)" (PDF). In Moehlman, P.D. (ed.). Equids: Zebras, Asses and Horses. Status Survey and Conservation Action Plan. IUCN/SSC Equid Specialist Group. Gland, Switzerland and Cambridge, UK: IUCN. pp. 82–92.
- Wilford, John Noble (11 October 2005). "Foal by Foal, the Wildest of Horses Is Coming Back". New York Times.
- "Financial losses puts at risk Chinese program of reintroducing Przewalski's horses". Welcome2Mongolia. Archived from the original on 29 May 2009.
- [no title given]. PBS (video).
- Chen, Xia; Huang, Shan (28 December 2007). "Returning Home — Przewalski's horse reintroduction project". China.org.cn.
- "Przewalski's horse - Equus ferus przewalskii". IUCN SSC Equid Specialist Group.
- Slivinska, Kateryna; Kopij, Grzegorz (2011). "Diet of the Przewalski's Horse Equus Przewalskii in the Chernobyl Exclusion Zone". Polish Journal of Ecology. 59: 841–47.
- Scheibe, KM; Eichhorn, K.; Kalz, B.; Streich, WJ; Scheibe, A. (1998). "Water consumption and watering behavior of Przewalski horses (Equus ferus przewalskii) in a semi-reserve". Zoo Biology. 17 (3): 181–192. .
- Brinkmann, Lea; Gerken, Martina; Riek, Alexander (2012). "Adaptation Strategies to Seasonal Changes in Environmental Conditions of a Domesticated Horse Breed, the Shetland Pony (Equus ferus caballus)". Journal of Experimental Biology. 215 (7): 1061–1068. PMID 22399650.
- Ferreira, Luis Miguel M.; Celaya, Rafael; Benavides, Raquel; Jauregui, Berta M.; Garcia, Urcesino; Sofia Santos, Ana; Rosa Garcia, Rocio; Miguel; Rodrigues, Antonio M.; Osoro, Koldo (2013). "Foraging Behaviour of Domestic Herbivore Species Grazing on Heathlands Associated with Improved Pasture Areas". Livestock Science. 155 (2–3): 373–383. .
- McCue, Molly E.; Bannasch, Danika L.; Petersen, Jessica L.; Gurr, Jessica; Bailey, Ernie; Binns, Matthew M.; Distl, Ottmar; Guérin, Gérard; Hasegawa, Telhisa; Hill, Emmeline W.; Leeb, Tosso; Lindgren, Gabriella; Penedo, M. Cecilia T.; Røed, Knut H.; Ryder, Oliver A.; Swinburne, June E.; Tozaki, Teruaki; Valberg, Stephanie J.; Vaudin, Mark; Lindblad-Toh, Kerstin; Wade, Claire M.; Mickelson, James R.; Georges, Michel (12 January 2012). "A High Density SNP Array for the Domestic Horse and Extant Perissodactyla: Utility for Association Mapping, Genetic Diversity, and Phylogeny Studies". PLOS Genetics. 8 (1): e1002451. PMID 22253606.
- Goto, Hiroki; Ryder, Oliver A.; Fisher, Allison R.; Schultz, Bryant; Pond, Sergei L. Kosakovsky; Nekrutenko, Anton; Makova, Kateryna D. (1 January 2011). "A massively parallel sequencing approach uncovers ancient origins and high genetic variability of endangered Przewalski's horses". Genome Biology and Evolution. 3: 1096–1106. PMID 21803766. Archived from the originalon 27 July 2015.
- Heptner, V.G.; Nasimovich, A.A.; Bannikov, A.G.; Hoffman, R.S. (1988). Mammals of the Soviet Union. Vol. I. Washington, DC: Smithsonian Institution Libraries and National Science Foundation.
- JSTOR 1776930.
External links


- "images and movies of the Przewalski's horse (Equus ferus przewalskii)". ARKive. Archived from the original on 7 May 2006.
- "Details of the re-introduction program for Przewalski's horse".
- "Umbrella organization of all institutions participating in the reintroduction of takhis in Mongolia". Archived from the original on 28 September 2006.
- "Przewalski horse conservation organization, reintroduced the species to Mongolia in 2004 and 2005 and continues research and conservation on the Mongolian steppe". Association Takh.