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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.origins
Subject: Re: Sharks
Message-ID: <1164@utastro.UUCP>
Date: Tue, 26-Mar-85 11:44:36 EST
Article-I.D.: utastro.1164
Posted: Tue Mar 26 11:44:36 1985
Date-Received: Fri, 29-Mar-85 03:19:23 EST
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Organization: U. Texas, Astronomy, Austin, TX
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> 
> The coelecanth's persistence is entirely consistent with punctuated
> equilibrium; one can simply say that it inhabits a niche which has stayed
> relatively unchanged for the past however-many-million years, and that the
> population is large enough to prevent substantial genetic drift.  (Of
> course, it helps to back this up with enough info on the lifestyle of
> coelecanths to show that the niche at least might be as old as the fish.
> I should, but I don't know much at all about coelecanths).  I also don't
> know enough about evolutionary theory to give an equivalent argument in
> gradualist terms; any takers?
> 
> Robert Thau

As I understand it the difference between gradualism and punctuated equilibrium
models has to do with the pacing of evolution.  Both schools would agree that
a stationary isolated ecological niche inhabited by a well-adapted organism 
would not give the opportunity for morphological change.  Biochemical change 
would occur, but would not show up in the fossil record.


"Don't argue with a fool.      Ethan Vishniac
 Borrow his money."            {charm,ut-sally,ut-ngp,noao}!utastro!ethan

*Anyone who wants to claim these opinions is welcome to them.*