> is isn't it true that new species don't arise through interbreeding between
> different species because different species cannot produce fertile
> offspring. I say this because the definition of a species is the ability to
> produce fertile offspring, if two individuals mate and produce a fertile
> offspring , they aren't different species , so a new species could not arise
> by the mating of individuals from a different species.
Apparently Dolphins and False-Killer Whales, although different breeds do, when interbreed, give birth to fertile offspring. Tigers and Lions when interbred also have fertile offspring. There are probably others but those two came to mind quickly from a paper I recently read on the subject. What I do recall reading however is that the idea that hybrids are now thought to play a much greater role in plant evolution than was previously the case because of the quicker ability of hybrids to fill ecological niches. Whether this idea gains much currency beyond botany I can't say but I suspect we still have much to learn about how different species evolve.
John Thornton