Hard Luck Cheetah
Cheetah; Acinonyx jubatus. Gerald and Buff Corsi © California Academy of Sciences
DB: This is Earth and Sky. Cheetahs are the most ancient of the big cats . . .they’ve been on Earth for four million years.
JB: But fewer than 15 thousand cheetahs are left . . . and they’re tough to breed in captivity. In the 1980s, it was hoped genetic testing would show why. That’s when an African game park sent blood samples from 70 cheetahs to Dr. Stephen J. O’Brien at the Laboratory of Genomic Diversity in Maryland. The test results were hard to believe. Every cheetah was genetically identical.
Stephen J. O’Brien: There was no diversity at all. And so I had actually commented to the veterinarian….who’d collected this material, that perhaps he was trying to trick the lab scientist by simply collecting a single cheetah, and splitting up the sample into 70 different tubes.
DB: All the world’s cheetahs are thought to be as genetically alike as identical twins. With no genetic diversity, they suffer the costs of inbreeding – susceptibility to disease, genetic defects, and reproductive abnormalities such as low sperm count.
JB: Scientists believe the cheetah barely survived a mass extinction 12 thousand years ago – by the inbreeding of a few, closely related survivors. Cheetah conservationists are now working on ways to enhance breeding through artificial insemination, and in vitro fertilization. Thanks today to the U. S. Fish and Wildlife Service and to the National Fish and Wildlife Foundation. We’re Block and Byrd for Earth and Sky.
Our thanks to:
Stephen J. O’Brien
Chief Laboratory of Genomic Diversity
National Cancer Institute
Frederick Cancer Research and Development Center
Frederick, Maryland
Links:
Author’s Notes:
According to Stephen J. O’Brien, “it was in the early 1980s when the people who were managing zoos were changing over from being collectors of wildlife and displayers to breeders and conservators of wildlife. And they discovered that many of the large cats bred very well – lions and tigers, mountain lions, ocelots. But there was an exception which was the African cheetah…in fact, there were so few offspring born that the population in captivity was only being sustained by capturing new wild animals. And that was a rather worrying situation to the zoo directors and curators.”
He said the genetic tests “all showed pretty much the same thing: that the cheetah had lost about ninety-nine percent of the overall variability that its ancestors had carried.”
“The cheetah had the bad luck to have descended from a very tiny ancestral population that probably almost went extinct, but just barely survived by a whisker, “ said O’Brien.
He added that he is “cautiously optimistic” about the potential of cheetahs to survive as a species. “I think that the cheetah’s survival through this historic population bottleneck of many thousands of years ago to increase to tens of thousands, perhaps hundreds of thousands up until that last century shows that the cheetah’s intrinsic genetic resilience is pretty good. The drop that’s happened most recently has been has been largely the familiar story of habitat depletion and simply the human agricultural expansion throughout its range.”
He said, “I think that if people as a whole who live in the range of the cheetah make a decision that they want to turn around the extinction process, that this can happen. The cheetah is a glorious evolutionary creation. It took millions of years of natural selection and adaptation and wonderment to produce this thing. And I think it’s certainly as valuable and as worth saving as any painting hanging in the Louvre today.”
Akbar, the sixteenth century emperor of India, kept thousands of cheetahs. He may have been the first to realize the difficulty in breeding cheetahs in captivity.
To increase genetic diversity in captivity, zoos and conservation programs take great care to make sure that only unrelated animals mate.
Other info:
O’Brien, Stephen J., Cheetahs Never Win and Other tales from the Genetic Frontier (working title). Due to be published summer 2003 by St. Martin’s Press, New York, NY.
Additional Teacher Resources
Public Broadcasting Service, Nature, Critter Guide: Mammals: Cheetah.
This site provides a brief natural history of the cheetah including where they live, what they eat, their social habits, fun facts, and links to more information.
International Society for Endangered Cats, Fact Sheet: Cheetah
This site provides a comprehensive fact sheet of the cheetah including its description, habitat, range, reproduction, social structure, hunting methods, and a variety of links to more information on the cheetah.
Cheetah Conservation Fund: Genetic Diversity
This site explains the natural history of the cheetah spanning back twenty thousand years ago when it roamed throughout four continents: Africa, Asia, Europe, and North America. Also discussed is the cause and effect of how cheetahs exhibit much lower levels of genetic variation than other mammals.
