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Re: Defending grades (Was: Re: Archaeopteryx (rant))

Quoting Dinogeorge@aol.com:

> They need not be. All we need to do is recognize the appearance of an 
> evolutionary novelty (a change in a character's state, or the appearance of a
> new 
> character, for example). When one appears, it is valid to assert that a
> species 
> has changed into another.

Well, no, it is valid to assert that some members of a species have a 
different character state, or a new character.  I'd like to know how you know 
they couldn't still interbreed with the parent species.

Which brings me back to the question of paraphyletic species being created 
when they split.  Why should we necessarily put either population in the 
original species?  Just because one of the new groups looks just like the old 
one doesn't necessarily mean members of the conservative new group could 
interbreed with members of the old.

Nick Pharris
Department of Linguistics
University of Michigan