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RE: species



        All this yammering about species concepts... It's nice to see
science (of a sort) on the list again. I just thought it an appropriate time
to point out that the phylogenetic species concept is not (as George
suggested) at all ludicrous. It doesn't even seem to be it's own concept, at
least not as far as requiring that a species ceases to exist as soon as it
spawns daughter species. 
        Back to first principles:
        Look at the *biological* species concept: "a group of continuously
interbreeding populations" (paraphrased). This concept seems to be applied,
or at least concieved of, outside of an historical context. When we place it
in an historical context, what happens? When one or more populations becomes
reproductively isolated from the group, is the original species changed?
        The answer is a resounding "YES". The morphology of one group of
populations may not have changed, but note that we are not discussing a
*morphological* species concept, are we? The original collection of
interbreeding populations NO LONGER EXISTS. Instead, we have two (or more)
smaller collections of interbreeding populations, with correspondingly
different genetic compositions and "potentials" (if you will). One or the
other may go on to change morphologically, maybe both will. However,
according to the biological species concept, both are new species.
        So, you ask, what is one or more populations goes extinct? Won't
that change the species as well. My answer is, I don't know. Personally, I
think the idea is impractical anway, since we can only recognize speciation
by morphological change anyway (as I believe George has argued before). I
just wanted to point out that the PSC is not some sort of communist plot.
        Wagner
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    Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
                    "...To fight legends." - Kosh Naranek