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(This article is one opinion item explaining why the okapi, Okapia johnstoni, is the probable hybrid origin. It"s part of the support material for the alternate theory the evolution readily available on this website.)
Okapis mix properties otherwise seen only separately either in the giraffe or in the zebra, and also under simple circumstances this fact would constitute strong evidence the okapis are giraffe-zebra hybrids. And also yet, it seems no scientist has actually investigated this possibility. Why?
Well, apparently, scientists rely an ext on theory in this situation than on observation. In trees representing welcomed notions of evolution descent, giraffes and zebras are inserted on widely different branches, so the is generally believed that the 2 are just too far apart to develop hybrids. Thus, that is no surprising that there are no reports native researchers that tried to create such hybrids. Testing does no occur because theory says it’s useless to try.
Scientists long back assigned the okapi and also the giraffe come the very same taxonomic order (Artiodactyla) since they both have cloven hooves, and to the same family members (Giraffidae) because they share certain distinctive features: Both have large eyes and ears, thin lips and also an extraordinarily long, extensible tongue that enables them to lick their entire faces, also the ears; their backs slope upward from rump come withers; they also share the exact same dental formula: (i 0/3, c 0/1, pm 3/3, m 3/3) × 2 = 32. Both okapis and also giraffes, unlike any type of other mammal, have actually molars v rugose enamel and also bony horns that stay covered with skin throughout life (Nowak 1999, vol. 2, p. 1085). The two are thus firmly linked.
Yet the rump and legs of an okapi space covered through black-and-white stripes exactly like those of a zebra. Perhaps, then, if okapis had solid hooves instead of cloven ones, they would certainly be classified as perissodactyls (Order Perissodactyla) and would it is in considered an ext closely related to zebras than to giraffes? one okapi is about the very same size together a Burchell’s zebra.
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The chromosome count of one okapi is likewise like that of a zebra, come which it is not claimed to be related, and unlike that of a giraffe. Giraffes have 30 chromosomes (Taylor et al. 1967; Hösli and Lang 1970; Koulisher et al. 1971), conversely, okapis have actually a variable chromosome variety of 44-46, depending upon the pet in question; most seem to have actually 2n = 45 (Ulbrich and Schmitt 1969; Hösli and also Lang 1970; Koulisher 1978). The chromosome variety of Grevy’s zebra is 2n = 46 and also plains zebras have 2n = 44 (Benirschke and also Malouf 1967). Sports in chromosome count is chin unusual among mammals, however common in hybrids.
Okapis also produce high level of abnormal sperm, i beg your pardon is continuous with the idea that they are the commodities of a distant hybrid cross. Thus, Penfold (2007) reports that 52% percent that the spermatozoa developed by these pets are form abnormal (abnormal sperm is characteristics of hybrids). As those authors state, “okapi semen collected by electroejaculation routinely contain high number of non-motile and also plasma membrane-damaged spermatozoa, reportedly unrelated to season or the length of time since the male was housed v a breeding female.” various studies report the okapis have poor reproductive success (Benirschke 1978; Leus 2004; Loskutoff 1997; Rabb 1978; Raphael 1988; Raphael et al. 1986; van Puijenbroeck and also Leus 1996), simply as is the instance with plenty of kinds of hybrids.
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Zebra (left), okapi (center) and giraffe in silhouette. The general conformation of one okapi is intermediate. Okapis are about the exact same size together zebras. Giraffes (not shown to scale) weigh 2-3 times as much.
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It is, that course, renowned that giraffes and also zebras exist in mixed herds in miscellaneous parts the Africa, and therefore are in potential reproduction contact (these regions incorporate those where okapis occur).