Once quite widespread throughout Asia and Africa, there has been a large reduction of the cheetah's habitat and numbers though it is still seen in widely separated areas of Africa. Recent surveys of cheetah populations have shown that there is almost no genetic variation among individuals, even among those taken from the furthest points of its range. This is due to an evolutionary "bottleneck" caused by the fact that at one point cheetah populations crashed to very low numbers and then expanded from the same stock. As a result cheetahs in the wild, as well as in captivity, show several problems due to inbreeding which is threatening its future survival. The problems encountered are low sperm counts leadin g to reproductive difficulties, low survival of juveniles, morphological aberrations and high susceptibility to diseases because of low genetic diversity in the immune system. Thus, even when numbers seem relatively adequate for a given species, a low genetic diversity can increase its vulnerability to extinction.