It's not an on/off switch. The withdrawal of two species from each other is gradual, like when horses and zebras, or lions and tigers produce offspring that are either sterile, or not particular well suited to either the lion's or the tiger's means of existence. Speciation is an arbitrary choice made by humans as to where to draw the line. Lions and Tigers produce viable offspring--do you think they are of the same species? If so, you had better alert the Smithsonian, because they will be awfully surprised to hear it.
You are making rules for an oversimplified model of the world we've developed for cataloging purposes, and demanding that they obey natural laws of your own devising. Better be prepared to wait for a while.
I didn't make the rules, Darwinists did.
They're the ones who say all species derived from common ancestry, through "natural selection" and "speciation".
Lions and tigers may be different "species" (well, by your definition of species, another person on this thread used a completely different definition), but the fact that they are obviously related and can interbreed means they are not evidence in support of Darwinistic macroevolution.
I am looking for the evidence in support of the topic of discussion.