True - I guess examples like these ants, or lions and tigers, where we have DNA available for both, give a better idea of the speed of genetic drift, or at least some datapoints. We can compare the DNA, and estimate how long those numbers of changes took to accumulate, without yet having got to the point of no return.

I wonder what are the most visually, or structurally, or genetically, different animals that can still interbreed. Things like lions & tigers, polar bears & grizzlies, and zebras & horses, come to mind ... what else ?!