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

Richard Zander Richard.Zander at mobot.org
Mon Apr 13 09:04:01 CDT 2009

You cannot refute the points I am making by making true statements about
other things. 

Classification should be based on evolution, most of us agree. My
central point is that alpha taxonomy has the best grip on
evolution-generated groupings, and that molecular analysis can
demonstrate direct evolutionary relationships (paraphyly-autophyly
series) between such groups as ancestor-descendant relationships (that
is, involving descent with modification of taxa). 

Classification by holophyly eliminates this information. The "natural"
taxa are already classified by alpha taxonomists, and are chock full of
evolutionary information that molecular analysis can reveal. Molecular
analysis can let one know when one taxon is in the wrong cluster and
point out the right cluster but otherwise the classification is already
there in the original evaluation by an alpha taxonomist.

Discovery of paraphyly, "massive homoplasy," and "cryptic" taxa has been
misinterpreted. These features are evolutionary information and should
not be hidden by burying them (in synonymy or splitting into new names)
in phylogenetic classifications.

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
Non-post deliveries to:
Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Mario Blanco
Sent: Sunday, April 12, 2009 5:34 PM
Subject: Re: [Taxacom] burn out (was: classification of Class Rosopsida)

Richard Zander wrote (in brackets):

[ The reason some of us insist on paraphyletic taxa is because
if defined as descent with modification, is described only by
paraphyletic-autophyletic series, where the paraphyletic taxon is the
descendee (ancestor), and the autophyletic taxon is the descender. ]

   Not true. Evolution does not require a classification to be 
described. If you meant "represented" instead of "described", then your 
statement is also erroneous. Evolutionary history can be represented by 
a cladogram, and can be summarized by a series of monophyletic clades 
nested in other (monophyletic) clades. You can circumscribe every clade 
so they are all monophyletic.

[ In a phylogenetic cladogram with paraphyly eliminated, we know what
descender is, it is the exemplar, but we don't know what the descendee
is, it is only a node, without diagnosis or any real biological
attribute. ]

   A cladogram by itself does not have paraphyly or monophyly. Those are

attributes of classifications. If you meant to say "phylogenetic 
classification" instead of cladogram, then your are implying that in a 
paraphyletic classification you know the "descendee" (I guess you mean 
ancestor), which you do not know by just looking at the names of taxa in

either type of classification. Just by looking at a group of names of 
families in a paraphyletic classification, you cannot know if one of 
them originated from another. In a phylogenetic classification, at least

it is safe to assume that none of them originated from another taxon in 
the same rank.

[ The central stem of a phylogenetic lineage is a series of
nothings. ]

   It is a series of hypothesized ancestors. Same as in a paraphyletic 
classification. Again, you are confusing cladograms with

[ ONLY demonstration of descent with modification of taxa will
evolution. This may be done in several ways, but demonstration of
paraphyly should be the one way systematists should try to preserve by
not enforcing holophyly in circumscribing taxa. ]

   Again, an explanation of the evolutionary process does not require a 
pre-existing classification. You are stating your preference of 
classification methodology as if it was a fact.

Mario Blanco


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