In a new study published in the open access journal Genome Biology, an international team of researchers found that the cheetah (Acinonyx jubatus) descended from a distant relative of the American puma. The genome studies conducted on 18 different individuals showed little genetic diversity.
Toward the end of the Pleistocene period, about 100,000 years ago, these early ancestors of the American puma, a now extinct species called Miracinonyx inexpectatus, Miracinonyx studeri, and Miracinonyx trumani, migrated to Asia and then south toward Africa after crossing the Bering Sea land bridge.
Migration and genetic bottlenecks
This first migration was also responsible for the first genetic bottleneck in their population. During this first migration, the climate was still in turmoil, punctuated with frequent periods of glaciation. With the vast territorial boundaries of individuals, a limited gene pool was created. Territories covered from 300 to 800 square miles, and resulted in incestuous mating and therefore, a limited gene flow, causing a decrease in the big cats numbers.
A second bottleneck occurred between 10,000 and 20,000 years ago, further reducing the cheetah’s numbers, and leading to a further lowering of their genetic diversity. This period of time, the end of the ice age, was marked by the retreat of the glaciers and the extinction of the early cheetah ancestors in North America, as well as other large animals, like the saber-tooth tiger.
The results of their travels have given cheetahs a very low genetic diversity, anywhere from 90 to 99 percent less than other animals. Today’s cheetahs have difficulty reproducing, even in captivity, and suffer from very low sperm counts, low sperm motility and deformed flagella. To demonstrate their low genetic diversity, skin grafts between unrelated cheetahs show no rejection of the donor skin as if they were identical twins.
The research led to the conclusion that having this information would be useful in any efforts in sustaining this endangered species and increasing their numbers in their present range. There are presently about 6,700 cheetahs left in the wild in Africa. They are capable of going from 0 to 60 mph in a mere three seconds and have been clocked at over 70 mph while in pursuit of prey.
This very interesting study, “Genomic legacy of the African cheetah, Acinonyx jubatus,” was published in Genome Biology on December 10, 2015.
