paraphyletic evolution

[Curtis Clark]

At 11:08 AM 00.02.05 -0800, Ken Kinman wrote:
>    I was delightfully "stunned" when you started challenging another
>strict
>cladist (Tom DiBenedetto).  You might become a cladisto-eclecticist yet.

Not a chance! :-)

>    If most speciation is budding (paraphyletic), then you cannot cut a
>continuous tree of life without creating paraphyletic groups.

I'm tempted to say that any idiot can see the difference between a
paraphyletic group of species and a stem species with peripheral isolates.
But unfortunately, I have no data to back up that assertion. At any rate,
IMO calling that stem species paraphyletic is as un-useful as calling
Michael Donoghue paraphyletic. Paraphyletic groups are not natural because
it requires human judgment to decide which clades to remove and which to
leave, and any two investigators may have different ideas. A stem species
with peripheral isolates is natural, because *all* of the species it
spawned are no longer a part of it--no opinions required.

> The only
>reason cladistic classifications work is because extinction and a
>fragmentary fossil record have left us with huge gaps in that tree of
life.

Well, actually, no, that's why "eclectic" classifications work. Those
numerous apomorphies that you believe separate birds and reptiles arose
more or less one at a time. If there were still extant a fair
representation of those "intermediate" forms, none of us might ever
consider making the separation between birds and reptiles. (Even so, the
similarities between birds and crocodylia are as striking as the
differences.)

>Hennigian assumptions and methodologies work most of the time, UNTIL the
>gaps start getting smaller (and this naturally happens at species level
>more
>quickly than at higher taxonomic levels).

It has nothing to do with gaps. It has everything to do with pattern of
descent.

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Curtis Clark                  http://www.csupomona.edu/~jcclark/
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