These bottlenecks are interesting.

The cheetah had an extreme bottleneck — the remaining 20K or so cheetahs are so genetically close that they can take each other.

I remember when this was figured out reading that the estimate was that they had gone down below a hundred, a few kiloyears ago.

Here’s a brief article from back the (1987) about this: https://www.washingtonpost.com/archive/politics/1987/02/16/c...