Inadequacy of cladistics

Richard.Zander at MOBOT.ORG Richard.Zander at MOBOT.ORG
Fri Jan 23 12:37:05 CST 2004


I think I agree. Cladistics is essentially a cluster analysis that groups
taxa. The theory is simplistic, and details of process are ignored. Of
course, we don't know details of process for most taxa, so as long as
cladists state we are using a simple model to cluster OTUs, and are not
reconstructing a process, that's okay. The problem, is, as you say, that
there is a confusion between such.

In molecular terms, finding similarities between introns shows
relationships, finding dissimilarities between exons shows process. I think.

______________________
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
Fax: 314-577-9595
Websites
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-----Original Message-----
From: Thomas G. Lammers [mailto:lammers at vaxa.cis.uwosh.edu]
Sent: Friday, January 23, 2004 12:07 PM
To: Richard.Zander at MOBOT.ORG; TAXACOM at LISTSERV.NHM.KU.EDU
Subject: Re: Inadequacy of cladistics


At 11:55 AM 1/23/04, Richard.Zander at MOBOT.ORG wrote:
>Excellent thought. What is this fundamental inadequacy?

Your points are valid, but my criticism has always been the poor
correlation between cladistic methodology and biological reality.

Evolution is NOT perpetually dichotomous.  In plants at least, there is a
great deal of reticulation.  Paraphyly is real; a parental population does
not speciate when it gives rise to a daughter species.  Etc.

Since the early years of the 20th century, we have learned a great deal
about the complex array of diverse biological phenomena by which species
come into existence.  With cladistics, we have chucked all that out the
window and chosen to represent it by a gross oversimplification of the
process.  Those pretty stick figures are utterly detached from the complex
reality they purport to represent.

Cladograms may be objective, testable, and repeatable, but if the procedure
by which they are created IGNORES underlying biological reality, they are
(pardon the horribly mixed metaphor) a house of cards with feet of clay,
built on sand.




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