[Taxacom] burn out (was: classification of Class Rosopsida)

[Richard Zander]

Mario:

A paraphyletic group in a classification is so because it was found to
be paraphyletic in a cladogram. If we keep different names for the
paraphyletic group and the autophyletic taxon (that which makes the
group paraphyletic if recognized at a proper level to flag its unique
evolutionary qualities), then we have different names in the
classification. If we combine the names into one to enforce holophyly,
then the cladogram retains the relationship information but the
classification does not. The relationship information in the cladogram,
however, does not include the unique evolutionary traits of the
autophyletic taxon since these were either not in the data set to begin
with or were eliminated as autapomorphies after generation of the
cladogram. Thus, classification (names for things) and cladograms
(sister-group relationships) and evolution (ancestor-descendant
relationships) are intertwined, and there is information available in
systematic analyses about all three. All such information should be
preserved, since all contribute to science. 

Some of the logical fallacies you detect may be just different
definitions of terms or different assumptions or just misunderstandings.
Also, I'm quite an advocate of paraconsistency. Depends on results, you
know. :)

No, I do not want static classifications, or expect them. I just do not
want artificial (holophyletic) classifications passed off as wonderful
products of a new paradigm in evolutionary science (analysis of
sister-group relationships). It's not a paradigm, it's just a method of
inferring sister-group relationships, which are not the be-all and
end-all of evolution as applied to systematics.

Alpha taxonomy is not just describing species. See
http://en.wikipedia.org/wiki/Alpha_taxonomy
We also describe higher taxa.

Oh, and I'm also a phylogeneticist, just like you, in that I treasure
information about sister-group relationships generated by any clustering
method, including parsimony. I think, however, that classification
should preserve ancestor-descendant relationships, too, and thus rather
style myself an evolutionary taxonomist. See
http://en.wikipedia.org/wiki/Evolutionary_taxonomy 


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Richard H. Zander 
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Missouri Botanical Garden
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richard.zander at mobot.org
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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 Mario Blanco
Sent: Tuesday, April 14, 2009 11:14 AM
To: TAXACOM
Subject: Re: [Taxacom] burn out (was: classification of Class Rosopsida)

Richard,
I pointed out logical fallacies in your statements, which you use to
support your view that paraphyletic classifications are inherently
better than phylogenetic ones.

You say that "alpha taxonomy [taxonomists?] has the best grip on
evolution-generated groupings". This is necessarily a subjective
statement, because it depends on what you consider "best". Seems to me
that what you consider best are unchangeable classifications set only by
alpha taxonomists.

However, classifications have been constantly modified over time, not
just by molecular phylogeneticists; also by people using cladistic
methods with morphological traits, and for an even longer time,
exclusively by "alpha" taxonomists using no particular method of
analysis. Not to mention that, by definition, alpha taxonomy focuses on
species-level issues, not higher level classifications. You mean
traditional systematists, which many taxonomists are.

Besides, many taxonomists are also phylogeneticists (molecular or not),
or routinely collaborate with them; thus the distinction you want to
make is not clear at all.

I still cannot understand the logic in your statement that phylogenetic
classifications eliminate information on ancestor-descendant
relationships. You always have to refer to a cladogram or some other
type of evolutionary diagram to visualize these relationships. How does
a paraphyletic classification have more of this information? A
classification is just a series of names of taxa and associated ranks. 
You cannot see that one group descended from another just by looking at
a list of names in a paraphyletic classification.

Mario