Zebras (US: /ˈziːbrəz/, UK: /ˈzɛbrəz, ˈziː-/)[1] (subgenus Hippotigris) are African equines with distinctive black-and-white striped coats. There are three living species: the Grévy's zebra (Equus grevyi), plains zebra (E. quagga), and the mountain zebra (E. zebra). Zebras share the genus Equus with horses and asses, the three groups being the only living members of the family Equidae. Zebra stripes come in different patterns, unique to each individual. Several theories have been proposed for the function of these stripes, with most evidence supporting them as a deterrent for biting flies. Zebras inhabit eastern and southern Africa and can be found in a variety of habitats such as savannahs, grasslands, woodlands, shrublands, and mountainous areas.

Zebra

Temporal range: Pleistocene to recent 2–0 Ma 

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A herd of plains zebras (Equus quagga) in the Ngorongoro Crater in TanzaniaScientific classificationKingdom:AnimaliaPhylum:ChordataClass:MammaliaOrder:PerissodactylaFamily:EquidaeGenus:EquusSubgenus:Hippotigris
C. H. Smith, 1841Species

†E. capensis
E. grevyi
†E. koobiforensis
†E. mauritanicus
†E. oldowayensis
E. quagga
E. zebra

Modern range of the three living zebra species

Zebras are primarily grazers and can subsist on lower-quality vegetation. They are preyed on mainly by lions, and typically flee when threatened but also bite and kick. Zebra species differ in social behaviour, with plains and mountain zebra living in stable harems consisting of an adult male or stallion, several adult females or mares, and their young or foals; while Grévy's zebra live alone or in loosely associated herds. In harem-holding species, adult females mate only with their harem stallion, while male Grévy's zebras establish territories which attract females and the species is promiscuous. Zebras communicate with various vocalisations, body postures and facial expressions. Social grooming strengthens social bonds in plains and mountain zebras.

Zebras' dazzling stripes make them among the most recognisable mammals. They have been featured in art and stories in Africa and beyond. Historically, they have been highly sought after by exotic animal collectors, but unlike horses and donkeys, zebras have never been truly domesticated. The International Union for Conservation of Nature (IUCN) lists the Grévy's zebra as endangered, the mountain zebra as vulnerable and the plains zebra as near-threatened. The quagga (E. quagga quagga), a type of plains zebra, was driven to extinction in the 19th century. Nevertheless, zebras can be found in numerous protected areas.

Etymology

Taxonomy

Further information: Evolution of the horse

Zebras are classified in the genus Equus (known as equines) along with horses and asses. These three groups are the only living members of the family Equidae.[8] The plains zebra and mountain zebra were traditionally placed in the subgenus Hippotigris (C. H. Smith, 1841) in contrast to the Grévy's zebra which was considered the sole species of subgenus Dolichohippus (Heller, 1912).[9][10][11] Groves and Bell (2004) placed all three species in the subgenus Hippotigris.[12] A 2013 phylogenetic study found that the plains zebra is more closely related to Grévy's zebras than mountain zebras.[13] The extinct quagga was originally classified as a distinct species.[14] Later genetic studies have placed it as the same species as the plains zebra, either a subspecies or just the southernmost population.[15][16] Molecular evidence supports zebras as a monophyletic lineage.[13][17][18]

Equus originated in North America and direct paleogenomic sequencing of a 700,000-year-old middle Pleistocene horse metapodial bone from Canada implies a date of 4.07 million years ago (mya) for the most recent common ancestor of the equines within the range of 4.0 to 4.5 mya.[19] Horses split from asses and zebras around this time and equines colonised Eurasia and Africa around 2.1–3.4 mya. Zebras and asses diverged from each other close to 2 mya. The mountain zebra diverged from the other species around 1.6 mya and the plains and Grévy's zebra split 1.4 mya.[20]



Quagga mare at London Zoo, 1870, the only specimen photographed alive. This animal was historically considered a separate species but is now considered a subspecies or population of plains zebra.

The cladogram of Equus below is based on Vilstrup and colleagues (2013) and Jónsson and colleagues (2014):[13][20]

EquusZebras

Mountain zebra (E. zebra) 

Plains zebra (E. quagga) 

Grévy's zebra (E. grevyi) 

Wild asses

Kiang (E. kiang) 

Onager (E. hemionus) 

African wild ass (E. africanus) 

Horses

Horse (E. ferus caballus) 

Przewalski's horse (E. ferus przewalski

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