[Rduke55]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
Selection, like something else I won't mention, happens.

It's the notion of speciation that's got issues with logic.

[/ QUOTE ]

But you said populations could become mutually infertile with each other.
(That's what speciation is)

And what's the something you won't mention?

[/ QUOTE ]

Actually, I totally agree with him. Speciation really is a logically meaningless distinction. I mean, unless 'species' only means EXACTLY cannot mate with any other species. But even thats iffy, they can mate, with varying success, some of the times.

Calling two different things different species is a (nearly completely) arbitrary distinction. If that was Skidoo's point (I doubt it was) then I agree completely.

[/ QUOTE ]

That's what species are - reproductively isolated populations. they can interbreed with each thter and are infertile with other species.

[/ QUOTE ]

Hmmm. Its misleading at the very least, and it is pretty arbitrary. It just seems so...contrived. I understand that it IS contrived, and its meant as some sort of 'at the very least THIS different' type of line. But the amount of difference that might cause one particular set of groups, call them A and B, could be one single mutation. And in some other set, A' and B', they could accumulate hundreds of differences and still be able to reproduce if they were only reunited. And then they could be reunited. So they would be different species while they were on different islands, but the same species if we just moved them a few miles.

I know those are pretty impractical examples, in that groups with many, many mutations aren't likely to choose to mate with each other, but as long as they fit and as long as not too many of the mutations were to the reproductive machinery, etc...

I can buy it. I just don't like it.

[/ QUOTE ]

Speciation is certainly not a measure of genetic difference. It's what I said before about fertility.

In your examples, the first would be different species, the second would not be - even when they are on different islands.

[/ QUOTE ]

Are you sure about that? I don't think thats correct. I was under the impression that mutual infertility didn't HAVE to be because of a morphological or developmental barrier, but could be because of a behavioral one. Imagine if instead of seperate islands they are on seperate mating season schedules instead. This is theoretically identical to islands, except they see each other and interact but don't mate. They can not mate with each other, because one mates in the Spring wheras the other mates in the Fall, even though they could if they just tried. These count as different species, by my understanding...is that wrong? And then what happens if one group switches back to mating at the same time?

[/ QUOTE ]

That's where the other definitions come in.
Try the "cannot produce fertile offspring" idea.