We have been extremely fortunate in the past few weeks to have been tracking down and finding a female cheetah with her adolescent son. We are so lucky here at Londolozi to have a relatively large number of lions and leopards in the area, with the cheetah being an animal that is quite a rarity for us to see.
It’s not just at Londolozi, though, that these animals are rare. The global population of cheetahs is around 6,500 to 7,100, according to a list of threatened animals from the International Union for Conservation of Nature. Today, cheetahs are found in the wild in several regions in Africa (South Africa is home to around 1,300 of the global population) and a tiny population of another subspecies, the Asiatic cheetah, is found in Iran. The last four decades have seen a decline in cheetah populations of about 50%, as well as a significant reduction in the historic range of the species.
So why are these animals so rare and threatened? Scientists believe that cheetahs have already survived at least two extinction events in their history, and one of the main reasons behind these animals facing extinction today is due, in part, to surviving their last threats of extinction. We call these events genetic bottlenecks.
What is a bottleneck?
A genetic bottleneck occurs when a population is greatly reduced in size, limiting the genetic diversity of the species as there is fewer individuals to mate with.
Genetic exploration of cheetahs shows they may have survived two historical bottleneck events that have greatly reduced their population size. When a bottleneck occurs, the few remaining cheetahs end up mating with relatives. Inbreeding decreases the size of the gene pool, leading to complications such as declined genetic variability and possible mutations. This makes it more difficult for the remaining population to adapt to changes in their environment.
The first bottleneck event: Species Range Expansion
Cheetahs are believed to have descended from the same ancestors as the American puma. The first bottleneck that cheetahs may have experienced is thought to have occurred around 100,000 years ago, when they extended their range into Asia, Europe, and Africa. This range expansion is thought to have happened quite rapidly, dispersing smaller groups of cheetahs over a very large area, and restricting their ability to interchange genes.
The second bottleneck event: The Ice Age
The second probable bottleneck event took place about 10,000 to 12,000 years ago, near the end of the last ice age. During this bottleneck, the cheetahs of North America and Europe went extinct, and so only the Asian and African populations survived. Due to only a few surviving individuals, more inbreeding occurred, reducing the genetic variability on a greater scale.
A possible third extinction…
During the 19th century, the cheetah population had a great increase, and the global population grew to as many as 100,000. However, their genetic variability stayed low due to the extreme bottleneck events that took place thousands of years previously. In other words, their own genes pose a challenge to their continued survival. Because of their shallow gene pool, they have a low rate of reproductive success, and with fewer offspring, the population can neither grow nor adapt to changes in the environment. Along with this, cheetahs are facing pressure from climate change, habitat loss, and human activities.
… Or a species on the rise?
That being said, there are a plethora of positive predictions for the future of cheetahs. In South Africa, we are experiencing a significant cheetah population growth, thanks largely to a nongovernmental conservation project that carefully manages and rehabilitates cheetahs. Globally, the species has made a remarkable comeback in the past, so there is no reason why they can’t do this again.