Ring species make your definition non-transitive. The same with species that can interbreed but exhibit hybrid breakdown.

I invite you to examine the notes of the international ornithological congress... The difference between species and subspecies is quite subtle, and subject to interpretation, because no one is really going to do the experiment to find out if two individuals of geographically district populations can actually still interbreed.

So if you have a few grams of soil and want to know how many species of micro organisms are in there, you're setting them up with dates to see which ones will end up breeding?

One of a number of definitions. It is one that allows lions and tigers to be the same species.