Mules

Aren't mules kind of weird?

Let me get this straight. A male donkey and female horse can actually mate and form offspring.

Aren't they different species?

I thought nature is supposed to have safeguards against this. Put a sheep and pig together and you don't get fat, wooly, round creature. If you throw a goat and a cow into the same pen I don't think you can see some horned milking machine. At least the mule (or its counterpart, the hinney) is sterile! I guess that's the only safeguard.

More disturbing is that it's not just a horse and donkey that can be combined. Any of the equid species can get it on (want a striped donkey?)

As I write this, I googled, "Can a lion and a tiger mate?" Much to my chagrin, they apparently can! I used to think if you put a lion and a tiger in a pen you'd just get a dead lion or dead tiger. But now it turns out you could get a tiglon? Or a liger? Hopefully these things are sterile, at least... Sadly I don't know if the best answers will be found on the WWW for this question.

I would think however, that nature would prevent this sort of thing from happening... Overall I find this disturbing.