How do we define a "new" species.

I read that dogs and wolves can interbreed. Why are they considered different species?Also, can you shed any light on the peculiarity of the sterile mule?

I thought there might be some more technical reason--some physical difference. A wolf looks exactly like a dog to me.As regards the mule, I thought this was a special case. That donkeys and horses breed and produce this sterile blend. I assume donkeys and horses are different species?

Yeah, what I am trying to figure out is if there is some physical reason why two species can't breed--like a chemical reason or something.So I guess the mule is just a famous case. Why are they sterile?

I got it.Can we then say the following?:A "species" can be defined as an isolated gene pool---not isolated by some external factor, such as locale, but isolated because its DNA is not compatible with any other DNA. There are a few cases--such as wolves and dogs--which are accorded separate species-status more for traditional, cultural reasons rather than DNA incompatibility.

I was thinking that geographical isolation has nothing to do with it. You got a bunch of deer over here in the Northwest and another bunch of the same deer in the Northeast, and they never get together. Nonetheless they are the same species. (later, of course, much later, this situation might change--they evolve differently).As regards physical compatibility, I suppose you mean something like big dog/little dog. But they are the same species.There seem to be some exceptions. Hard to pin it down. I don't understand why DNA incompatibility would not be the deciding factor. Surely there are no cases where you have creatures that don't look alike having DNA compatibilities.

You're such an idiot. You just mentioned big dogs/little dogs.

I beg your pardon?If you meant that as a joke, you should have put a little smily face.If you did not mean it as a joke, well then you--you of all people--should not be making a comment like that.Talk about the pot calling the kettle black . . .This message has been edited by robinrohan, 01-26-2005 19:08 AM

You literal-minded jackass! Were you raised in a barn?Don't you understand that it is possible for a comment to be both serious and comic at the same time?It is possible to be serious without being solemn.If I put that smily face down, it would destroy any ironic comment I make. I will try to make it easy for you, duncehead. I will make the irony VERY OBVIOUS--okay?I know, there is a difference between the Internet and talking to someone face to face. I understand that you cannot detect the tenor of the person's voice on the Internet. But neither can you with a book!God, you make me sick!