The problem here is simply that the convenient, clean definition of species (mentioned in the thread many times) does not work so well in the real world.
Species is a fuzzy concept, and in mathematical terms, should be an equivalence relation (a always =a, (a=b)->(b=a), and (a=b & b=c)->(a=c), but is not.
Just because one has a definition, doesn’t mean s/he can go force the world to fit it.
Cliffy wrote:
My understanding’s no better than yours, but I remember from biology class that there are many different things which prevent reproduction between creatures, and womb space could certainly be one of them. In some beetle species, for example, members of different species look enough alike that they themselves can’t tell the difference and try to mate with each other. But their genitalia are incompatible and as soon as they start breeding, they figure it out and go searching for another partner. These beetles are classified as different species because they cannot reproduce with each other, even though this inability is caused by a physical factor (like womb size), not a genetic one. As we see, the exact definition of a species is not that clear.
As far as for what this has to do with evolution: more than it has been given credit for here. The talkorigins archive has some articles on ring species, but the gist is that Biblical creationism predicts certain unique “kinds” of animals, whereas evolution predicts much fuzzier boundaries like those seen in ring species.
Thanks to all who have posted.
Regards,
Shodan