If the horse parent is piebald (black and white) or skewbald (color other than black and white), the zorse may inherit the dominant depigmentation genes for white patches. Zorses are most often bred using solid-colored horses. Zorses combine the zebra striping overlaid on coloured areas of the hybrid's coat. The cladogram of Equus below is simplified from Vistrup et al. The horse lineage diverged from other equids an estimated 4.0 - 4.7 million years ago zebras and asses diverged an estimated 1.69–1.99 million years ago. Zebras are more closely related to wild asses (a group which includes donkeys) than to horses. See also: Equus (genus) § Taxonomic_and_evolutionary_history SubgenusĪfrican wild ass includes domestic donkey The difference in chromosome number is most likely due to horses having two longer chromosomes that contain similar gene content to four zebra chromosomes. Since none of the males are fertile, the females must be paired with either a donkey or a zebra. Haldane first recorded in 1922 that genetic hybrids are often inviable or sterile. The chromosome difference makes female hybrids poorly fertile and male hybrids generally sterile, due to a phenomenon called Haldane's rule. A hybrid will have a number of chromosomes exactly halfway between that of its parents for example, a cross between a horse (64 chromosomes), and a plains zebra (44 chromosomes), will produce a zebroid offspring with 54 chromosomes. In spite of this difference, viable hybrids are possible, provided the gene combination in the hybrid allows for embryonic development to birth. The zebra has between 32 and 46 chromosomes depending on the species. This is due to several chromosomal fusion and fission events during the evolution of equids. Living equids show wide variation in the number of chromosomes, ranging from a diploid number of 32 chromosomes in the mountain zebra to 66 in Przewalski's horse. Like mules and hinnies, however, they are generally genetically unable to breed, due to an odd number of chromosomes disrupting meiosis. In South Africa, they occur where zebras and donkeys are found in proximity to each other. These zebra–donkey hybrids are very rare. Donkeys are closely related to zebras and both animals belong to the horse family. Other names also include zebadonk, zebret, and zebronkey. Ī cross between a zebra and a donkey is known as a zenkey, zonkey (a term also used for donkeys in Tijuana, Mexico, painted as zebras for tourists to pose with them in souvenir photos), zebrass, or zedonk. Medium-sized pony mares are preferred to produce riding zonies, but zebras have been crossed with smaller pony breeds such as the Shetland, resulting in so-called "Zetlands". Ī zony is the offspring of a zebra stallion and a pony mare. Like most other animal hybrids, the zorse is sterile. The rarer reverse pairing is sometimes called a hebra, horsebra, zebrinny, or zebra hinny. This cross is also called a zebrose, zebrula, zebrule, or zebra mule. The combination of sire and dam also affects the offspring phenotype.Ī zorse is the offspring of a zebra stallion and a horse mare. Breeding of different branches of the equine family, which does not occur in the wild, generally results in sterile offspring. Many times, when zebras are crossbred, they develop some form of dwarfism. Generally, no distinction is made as to which zebra species is used. The different hybrids are generally named using a portmanteau of the sire's name and the dam's name. Zebroid is the term generally used for all zebra hybrids. Charles Darwin noted several zebra hybrids in his works. Zebroids have been bred since the 19th century. The offspring of a donkey sire and zebra dam, called a donkra, and the offspring of a horse sire and a zebra dam, called a hebra, do exist, but are rare and are usually sterile. In most cases, the sire is a zebra stallion. A zebroid is the offspring of any cross between a zebra and any other equine to create a hybrid.
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