[Taxacom] morphology in molecular phylogeny

[Richard Zander]

When morphology and molecular results conflict, the molecular results
are preferred because statistical analysis commonly demonstrates that
the results cannot be expected by chance alone at some significant
level, while morphological data is too sparse to analyze.

Thus, complaints about molecular analysis should deal directly with the
statistical basis of phylogenetic analysis, and whether it is indeed
adequate to reject morphological results when there is a conflict. This
is difficult, especially in that the statistics phylogeneticists use
(the "good" phylogeneticists, anyway) are more and more complex. It's
hard for phylogeneticists to keep up with new developments, much less
anyone else.



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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 John Grehan
Sent: Saturday, January 20, 2007 11:49 AM
To: Maarten Christenhusz; TAXACOM at MAILMAN.NHM.KU.EDU
Subject: Re: [Taxacom] morphology in molecular phylogeny

 
 Maarten Christenhusz wrote:
2. With phylogenies it should be attempted to include as many type
species as possible, and genera should be tested for monophyly on
multiple genes, and new taxonomy based on molecular studies, should also
have a morphological basis, since we can not check the genes when we are
in the field.

Here's the rub. When the two sources contradict each other completely
what is the phylogenetic and evolutionary meaning? As far as I can tell
there is no objective recipe for the answer. My own current inclination
is to place more emphasis on morphology if that morphology is strongly
corroborated since molecular approaches are fraught with phenetic
methodologies that obfuscate true apmorphies (for example the alignment
process introduces an entirely artificial and imaginary process into
base homology). But that's just my personal opinion. Others have
different opinions, but there appears to be a lack of some sort of
scientific, as opposed to ideological, resolution in modern systematic
theory. So in general most systematists either pretend the problem does
not exist by assuming faith in molecules or lumping everything together
based on some philosophical idealism.

John Grehan

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