[Go_Raiders]

Interbreeding is possible and occurs between species as well.

Canis lupus and Canis latrans (coyotes) have been observed interbreeding in Canada since the 1920’s.

Ursus maritimus (polar bear) and Ursus arctos (brown bear) are interfertile.

These are relatively recent divergences, but the mechanisms driving them don’t stop there and there have been billions of years for all the species to evolve from much simpler organisms. There is a really good overview at http://en.wikipedia.org/wiki/Evidence_of_common_descent

[ifinnegan]

“Interbreeding is possible and occurs between species as well.”

Then they aren’t different species.

They are subspecies.

But don’t worry about dogs. You said there are hundreds. What are some others.