[Taxacom] Fw: botany removed from highschool curriculum in USA]

[Richard Zander]

To be even more cynical, there is a bit of misdirection in the word "gene" in taxonomy, as in "gene tree." If it is a gene tree, then it is subject to selection and convergence between taxa, which will then be reflected in classification as false shared ancestry. If it is not a gene tree, and only a non-coding trait tree, we are basing our taxonomy on the "evolution" of gradually differentiating neutral traits in the genome, but selection is eliminated as a factor in evolution. Classification is then solely based on lineage splits without recourse to any additional information. But the cladogram is then not exactly a gene tree.
 
Although most publications in molecular systematics do refer to additional information on evolution that may be available, the final classification is almost always based entirely on the molecular tree. Because in real life molecular analysis involves both gene changes (and therefore possible convergence), and non-coding traits that are actually regulators and therefore involved in selection (and therefore possible convergence), and non-coding traits that are okay but insufficient in number or contradictory across sequences studied, and really great molecular traits (I think sines, certain indels) that offer only limited illumination, and horizontal gene transfer, and all the rest, I support the contention of certain taxacomers that evolution on which classification should be based should include serious consideration of addtional traits (autapomorphies, chromosome numbers, geographic distributions, and the now disreputable population genetics). 
 
The modern taxonomic process (as discussed offline with some others) is twofold. 1. An evolutionary analysis, like phenetics or parsimony and Bayesian phylogenetic study, then 2. classification. The evolutionary analysis is presently highly restricted in data it considers, such data is biased to a large extent, and the results involve a great deal of empty precision regarding real questions. There are some triumphs, but we should not let these give us false confidence in simplistic methods of evolutionary analysis.
 
_______________________
Richard H. Zander
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166 U.S.A.
richard.zander at mobot.org
 

________________________________

From: taxacom-bounces at mailman.nhm.ku.edu on behalf of Herbert Jacobson
Sent: Tue 10/6/2009 5:33 PM
To: schindeld at si.edu; releech at telus.net; taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Fw: botany removed from highschool curriculum in USA]



To be cynical, I don't why anyone on the list would be surprised since genes are the thing now in taxonomy, too.



Herb