cladism's greatest weakness
kinman at HOTMAIL.COM
Fri Sep 17 08:22:54 CDT 1999
I wish I had more time to respond to this right now. I don't see how
the evolutionary distance between the "first reptile" and the first bird is
very relevant (seems to just muddy the water). As for the problem of
"birdness", it is very similar to the problem we had and still have with
The continuity of evolution is such that cutting the evolutionary tree
is going to be arbitrary to some degree no matter how you do it.
Unfortunately, strict cladists have used Hennig's assumption to mask the
fact that they are just substituting one kind of arbitrariness for another.
At least eclecticists will admit to such arbitrariness, and I wish strict
cladists would eventually do the same, so we could start exploring this
fertile "middle ground" I have termed cladisto-eclecticism. For now I've
got to run (some of that "real" evolutionary work awaits my attention).
>From: Curtis Clark <jcclark at CSUPOMONA.EDU>
>Reply-To: Curtis Clark <jcclark at CSUPOMONA.EDU>
>To: TAXACOM at USOBI.ORG
>Subject: Re: cladism's greatest weakness
>Date: Fri, 17 Sep 1999 07:24:33 -0700
>At 11:10 AM 9/17/99 +0200, PIETER WINTER wrote:
> >The "different nature" of paraphyly at different levels is presented as
>some sort of obvious truth. I must have missed something. Can anyone
>elaborate on this? Surely they are both the results of the same process,
>separated only by time and extinction long after the event?
>If one accepts speciation as an evolutionary process, then a single
>speciation event separates a progenitor from its peripheral isolate. In the
>case of the Reptilia vs. Aves, a multitude of separate speciation events
>separate the first reptile from the first bird. People have to choose
>*which* speciation event (or in actuality the large and until recently
>virtually unknown ballpark that encompasses that speciation even) separates
>reptiles from birds. It is no longer an observation and interpretation of
>natural processes; it becomes a debate over "birdness".
>Curtis Clark http://www.csupomona.edu/~jcclark/
>Biological Sciences Department Voice: (909) 869-4062
>California State Polytechnic University FAX: (909) 869-4078
>Pomona CA 91768-4032 USA jcclark at csupomona.edu
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