two population bottlenecks that greatly decreased the genetic variability in populations; one occurred about 100,000 years ago that has been correlated to migration from North America to Asia, and the second 10,000–12,000 years ago in Africa, possibly as part of the Late Pleistocene extinction event. Genetics The diploid number of chromosomes in the cheetah is 38, the same as in most other felids. The cheetah was the first felid observed to have unusually low genetic variability among individuals, which has led to poor breeding in captivity, increased spermatozoal defects, high juvenile mortality and increased susceptibility to diseases and infections. A prominent instance was the deadly feline coronavirus outbreak in a cheetah breeding facility of Oregon in 1983 which had a mortality rate of 60%—higher than that recorded for previous epizootics of feline infectious peritonitis in any felid. The remarkable homogeneity in cheetah genes has been demonstrated by experiments involving the major histocompatibility complex (MHC); unless the MHC genes are highly homogeneous in a population, skin grafts exchanged between a pair of unrelated individuals would be rejected. Skin grafts exchanged between unrelated cheetahs are accepted well and heal, as if their genetic makeup were the same. The low genetic diversity is thought to have been created by two population bottlenecks from c. 100,000 years and c. 12,000 years ago, respectively. The resultant level of genetic variation is around 0.1–4% of average living species, lower than that of Tasmanian devils, Virunga gorillas, Amur tigers, and even highly inbred domestic cats and dogs. King cheetah The king cheetah is a variety of cheetah with a rare mutation for cream-coloured fur marked with large, blotchy spots and three dark, wide stripes extending from the neck to the tail. In Manicaland, Zimbabwe, it was known as nsuifisi and thought to be a cross between a leopard and a hyena. In 1926 Major A. Cooper wrote about a cheetah-like animal he had shot near modern-day Harare, with fur as thick as that of a snow leopard and spots that merged to form stripes. He suggested it could be a cross between a leopard and a cheetah. As more such individuals were observed it was seen that they had non-retractable claws like the cheetah. In 1927, Pocock described these individuals as a new species by the name of Acinonyx rex ("king cheetah"). However, in the absence of proof to support his claim, he withdrew his proposal in