Cheetah used as a feline rabbit lurcher in the U.K., 1937.
The Endangered Cheetah and Genetic Bottlenecks
The addition of the cheetah to the endangered species list last week was a sad blow to wildlife conservation groups that have fought hard to protect the species. However, in the past, the cheetah had been seen as a conservation success. What happened to drive the cheetah back to the brink?
The cheetahs didn’t need a push this time - the truth is, the species had never really recovered. Using outdated metrics, the cheetahs’ population had increased to the number that we believed was necessary for a chance at survival.
Unfortunately, the damage had already been done - the new cheetahs were descended from such a small population that there was little genetic diversity in this new population. To give you an idea how severely inbred the species has become, a skin graft from any cheetah can be put onto any other and will be accepted. Humans, on the other hand, have so much genetic diversity that there are probably members of your own family who would be too different for skin grafts to take.
When a population gets as small as the cheetah’s did in the past, there is no turning back. You can breed more animals, but the genes are lost forever. We can import genetically diverse members of another group, but since there are only ~15 cheetahs left in Asia, that’s not an option. Otherwise, it’s time to sit back and wait for mutation and evolution to take charge. This is a precarious position, though - the diversity of genes is what allows a species to adapt and to withstand external pressures, like famine, drought and disease - the lucky ones survive the hard times and the species gets stronger.
If genetic diversity gets as low as the cheetah’s, the whole species becomes vulnerable. Additionally, inbreeding will further damage the remaining animals and make survival ever harder for future generations, an effect known as inbreeding depression.
This indicates a weak and vulnerable population, as well as substantial inbreeding. Nothing terrible had to the cheetahs, this time - this was just a return to the effective population size. It was inevitable.