monophyletic/monothetic

Richard.Zander at MOBOT.ORG Richard.Zander at MOBOT.ORG
Thu Oct 2 12:59:58 CDT 2003


The monophyletic basis of cladograms is interesting in that lots of taxa are
naturally polythetic. There is a methodological assumption that monophyly =
monothetic.

Even if ancestral nodes are not considered ancestral taxa (necessarily
monothetic ancestral taxa), the analysis of mostly polythetic taxa through
monothetic sorting must generate some odd results.

I wonder what method would best evaluate evolutionary relationships of
polythetic taxa? Humm . . .  how about cluster analysis?

______________________
Richard H. Zander
Bryology Group
Missouri Botanical Garden
PO Box 299
St. Louis, MO 63166-0299
richard.zander at mobot.org <mailto:richard.zander at mobot.org>
Voice: 314-577-5180
Websites:
http://ridgwaydb.mobot.org/bfna/bfnamenu.htm
http://ridgwaydb.mobot.org/resbot/index.htm




-----Original Message-----
From: Scott L. Gardner [mailto:slg at UNL.EDU]
Sent: Thursday, October 02, 2003 11:58 AM
To: TAXACOM at LISTSERV.NHM.KU.EDU
Subject: [TAXACOM] follycode

The consequences for biological classification would obviously be
disastrous, but as a lan-
guage for scientific discourse the prospect is even more damning.
Consider again that, under
the PhyloCode, composition of taxa is unimportant, and change in
composition is unimpor-
tant; the only thing that is important is that a taxon is "monophyletic"
on any cladogram, even
when it refers to something completely different in composition
(meaning). Because the taxon
is always monophyletic on any cladogram, it has no scientific value
whatsoever. It is not a
scientific hypothesis, it is merely a definition, in words that are
divorced from reality. Propo-
nents of the PhyloCode have offered as their primary criticism of the
Linnaean system that it is
"essentialistic" as Nixon and Carpenter (2000) put it, how is the
PhyloCode less "essentialistic"

The PhyloCode should not be adopted, or even seriously considered, by
anyone. It is pure
folly.




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