Two bottlenecks for cheetahs?

Two bottlenecks for cheetahs?

In 1983, scientists found that the south African cheetah'sgenetic makeup had a potential flaw. The animal's lack of genetic variation, even more pronounced than that found in deliberately inbred mice or livestock, is striking. Thought to be caused by a population contraction, or "bottleneck," in the past--followed by excessive inbreeding--the genetic homogeneity has been blamed for this cheetah's poor reproductive performance. A recent look at the other subspecies in Africa, the east African cheetah, reveals the same story.

The genetic profile of the eastern cheetah is "only slightlymore variable" than that of the southern subspecies, according to a report in the January PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES (Vol. 84, No.2) from researchers in Kenya, the United States and Great Britain. The east African results suggest that two major population bottlenecks occurred in the cheetah population.

On the basis of recent data, the authors postulate that theprimary bottleneck happened 10,000 to 12,000 years ago during the late Pleistocene period, and the second happened during the last century. These dates appear consistent with reports that large numbers of mammals became extinct, or nearly so, about 10,000 years ago, and that the cheetah was hunted heavily at the turn of the 20th century.

The current study found sperm abnormalities in the eastAfrican cheetah to be as severe as those earlier found in its southern relative. Similar abnormalities in other species "would almost invariably be associated with infertility," according to the report. If the double bottleneck hypothesis is correct, captive crosbreeding programs using east African and south African animals together might improve the cheetah's genetic profile and chances for survival.