Zeedonk
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Image:Zonkey.jpg Image:Zeedonk 800.jpg A zeedonk (also spelled zedonk) (also known a zebrass, zebronkey, zonkey, zebadonk, zenkey or deebra) is an interspecies cross between a zebra and a donkey. The generic name for crosses between zebras and horses or asses is zebroid or zebra mule. Donkeys are closely related to zebras and both animals belong to the horse family. Zeedonks are very rare.
In South Africa they are called zonkeys and are fairly common where zebras and donkeys are found in close proximity. Like mules, however, they cannot usually breed, due to an odd number of chromosomes disrupting meiosis. However, in 1859's The Origin of Species, Charles Darwin reported a case of a zeedonk that apparently bred with a bay mare to produce a "triple hybrid."
Usually a zebra stallion is paired with a horse mare or ass mare, but in 2005, a Burchell's Zebra named Allison produced a zebrass called Alex sired by a donkey at Highland plantation in St. Thomas Parish, Barbados. Alex, born April 21st 2005, is apparently the first zeedonk in Barbados.
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Genetics
Donkeys and wild equids have different numbers of chromosomes. A donkey has 62 chromosomes; the zebra has 44. In spite of this difference, viable hybrids are possible provided the gene combination in the hybrid allows for embryonic development to birth. A hybrid has a number of chromosomes somewhere in between. The chromosome difference makes female hybrids poorly fertile and male hybrids sterile due to a phenomenon called Haldane's Rule. The difference in chromosome number is most likely due to horses having 2 longer chromosomes that contain similar gene content that contain the same genes as 4 zebra chromosomes.
Common wisdom states that hybrids only occur when the zebra is the sire, but the Barbados hybrid demonstrates otherwise. Two other known zebra hinnies have been foaled but did not survive to adulthood. The rarity of zebra hinnies indicates that the smaller number of chromosomes has to be on the male side if a viable hybrid is to be produced.
Zeedonks are interspecific hybrids bred by mating together two species from within the same genus. The offspring have traits and characteristics of both parents. Zeedonks vary considerably depending on how the genes from each parent are expressed and how they interact.
In captivity
Though zeedonks are rare, zoos have succeeded in producing them. Colchester Zoo in Essex claimed, erroneously, to have produced the first zeedonk in 1971. Zebra-ass hybrids dating back to 1815 were reported by Charles Darwin in 1859. A breeding program at the zoo in 1975 resulted in several hybrids. In Christmas week of 1975 Colchester Zoo's third zeedonk foal was born, the result of mating a donkey with different male zebras. Previous attempts at crossbreeding zebras with horses and donkeys had failed to produce surviving foals. The zoo's aim was to produce disease-resistant work-horses for Africa. Colchester Zoo experts believed their success was due to the use of an Arabian donkey (a variety not tried before in hybridization experiments) and were hopeful that the hybrids would be viable and fertile. A zeedonk is still exhibited at Colchester, but they now have a policy of preventing interbreeding and so will not be breeding more.
Colchester Zoo were, knowingly or unknowingly, repeating an experiment made by the Boers during the South African War when zebroids were bred as work animals. In that earlier experiment, Chapman's zebras and ponies were crossed to evolve a new animal for transport work.
In Origin of Species (1859) Charles Darwin mentioned four colored drawings of hybrids between the ass and zebra, including the famous cross made in 1815 by Lord Moreton of a donkey and a quagga. In The Variation Of Animals And Plants Under Domestication[1], published first in 1868 and a revised second edition in 1883, Darwin wrote: "I have seen, in the British Museum, a hybrid from the ass and zebra dappled on its hinder quarters." Darwin continued, "Many years ago I saw in the Zoological Gardens a curious triple hybrid, from a bay mare, by a hybrid from a male ass and female zebra," and expanded on his early report of Lord Moreton's quagga cross. Both works pre-date the claim from Colchester Zoo.
An "ass-zebra" is shown and described in Wonders of Animal Life (1930) edited by J A Hammerton. Crosses between Grevy's Zebra and the Somali Ass are reported from the same period.
Exotic animal breeders who house zebras sometimes breed zeedonks.
Trivia
Image:Zonkeyheadline.jpg On a recent episode of The Tonight Show With Jay Leno, Leno featured a newspaper clipping during his Headlines segment mentioning zonkies, perhaps believing it to be a mispelling of the word donkey.[2]
