[Taxacom] DNA only descriptions

[Richard Zander]

 
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Richard H. Zander 
Missouri Botanical Garden, PO Box 299, St. Louis, MO 63166-0299 USA 
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

Well, I don't know about single mutation-regulated morphological changes being unimportant. Suppose these changes ARE important evolutionarily? What then? 

A new single-locus trait that is morphologically quite different or multiplex (many expressed facets) is tested in selection. Even neutral traits must survive fitting in with a bauplan. Maybe a major morphological trait that is neutral and conservative originated in a single change in a regulatory gene and became the basis for a new evolutionary direction/taxon. It is conservative if the single change simply does not mutate often or if it is strongly selected against. If it is not conservative, then this becomes quite obvious. 

Numbers of molecular trait changes, particulary of non-coding sequences, do not trump expressed traits. Yes, you should give evolutionarily important traits a lot of weight, and determining importance means studying evolution, not determining evolution by numbers of traits.

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kim van der Linde
Sent: Friday, August 20, 2010 10:16 AM
To: Kenneth Kinman
Cc: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] DNA only descriptions


The more we study the evolution of traits at the molecular level, the more examples we get where large morphological differences are determined by minimal genetic differences, like a single point mutation in a regulatory element. Do I have to give such a morphological characteristic a lot of weight? Of course not.