[Taxacom] Evolutionary misconceptions

[Richard Zander]

Not all of us expect all species to anagenetically change over time into
something taxonomically new. There are many species that appear to be in
morphological stasis over thousands or millions of years, fixed by maybe
stabilizing selection, habitat tracking, boredom, I don't know what. The
basis of taxonomy is that taxa stay stable long enough to spread to some
extent about the earth.

So, neutral morphological traits do exist, and certainly surge about in
the phenome within (particularly diploid) species, and isolation of odd
combinations of slowly changing neutral traits can make a species. This
may operate in some taxa but not in others, so again I say that not all
species may be expected to anagenetically change over time into
something taxonomically new. 

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Richard H. Zander 
Voice: 314-577-0276
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166-0299 USA
richard.zander at mobot.org
Web sites: http://www.mobot.org/plantscience/resbot/
and http://www.mobot.org/plantscience/bfna/bfnamenu.htm
Modern Evolutionary Systematics Web site:
http://www.mobot.org/plantscience/resbot/21EvSy.htm
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-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Richard Pyle
Sent: Wednesday, March 10, 2010 11:46 PM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Evolutionary misconceptions
(was:Ladderisingphylogenetic trees)

We all seem to agree that eventually, with sufficient genetic isolation,
the descendants of that pregnant female will anagenize into something
with consistently different morphological traits/DNA
sequences/reproductive imperfections to the point that we would regard
the members of that descendant population as a distinct "subspecies"
from the descendants of the original population from which the pregnant
female came.