Understanding evolution problems

Richard.Zander at MOBOT.ORG Richard.Zander at MOBOT.ORG
Wed Mar 17 11:38:39 CST 2004

The gimmick, Pierre, that is used by cladists and statistical
phylogeneticists is jumping back and forth between results that may be used
for classification, and other results that may be used for evolution and
other studies. Classification may be based simply on a "best" result,
because classification is traditionally in flux, and traditionally
classification (e.g. a species) is what an expert taxonomist says it is.

But evolution and its use in guiding further research requires greater
reliability, so "best" is not good enough when second best is nearly as
good. Classification can be based on notions and conjectures because it is
easily corrected, but a scientific result from heavy-duty math and DNA
studies should be pretty damn rigorous and not just a "best result." It
should be much better than second best, and much better than the
probabilistic sum of second best and third best and fourth best, etc.
Statistical phylogenetics is only now addressing this problem.

When I say we need to meld phylogenetics and taxonomy, I mean create a
systematics that recognizes the difference between classifications based on
"best" results and those based on "reliable against all next best results."
An example of a mixture of the two kinds of classifications is the Tree of
Life project, which mixes both under the heading of "systematics" but many
(most in my opinion) details of branch arrangement are not reliable though
one might expect general reliability from a much trumpeted Tree of Life.

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
Bryophyte Volumes of Flora of North America:
Res Botanica:
Shipping address for UPS, etc.:
Missouri Botanical Garden
4344 Shaw Blvd.
St. Louis, MO 63110

-----Original Message-----
From: pierre deleporte [mailto:pierre.deleporte at UNIV-RENNES1.FR]
Sent: Wednesday, March 17, 2004 10:46 AM
Subject: Re: [TAXACOM] Understanding evolution problems

Dear Richard,

I really appreciate your warnings against over-resolution of topologies in
phylogenetics (of all kinds), and your connected comment that one needs to
become a phylogenetician in order to develop a useful critic. This vails
for phylogeny inference (evolutionary biology).

But as for classification, don't you perfectly know that an exact match
between phylogenetic topology-based classification and any character-based
classification is unattainable ? Not only phenetic overall similarity
matches phylogeny only under some peculiar evolutionary processes
(clocklike), but even synapomorphies may be labile in the evolutionary
process, and snakes are irremediably "legless tetrapods". Hence, what do
you suggest as for "melding rules"? Back to the "art of the systematician",
or anything new ? Any non-artistic, or as least artistic as possible,
melding rule ?

Present codes fix quite precious rules against ambiguity in alpha taxonomy
and nomenclature, and say nothing as for classification rules. Maybe wisely
so... But is the holy grail of the "unique, universal, fit-for-all-purpose"
classification rule anything else than an utopia ? Is a unique "best
possible" classification imaginable at all ? Or do different problems
require different relevant kinds of (optimal) classifications ?


A 09:09 17/03/2004 -0600, you wrote :
>That was irony. We need a counter revolution that re-melds taxonomy and
>phylogenetics into old definition systematics.
>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
>Bryophyte Volumes of Flora of North America:
>Res Botanica:
>Shipping address for UPS, etc.:
>Missouri Botanical Garden
>4344 Shaw Blvd.
>St. Louis, MO 63110
>-----Original Message-----
>From: Thomas G. Lammers [mailto:lammers at VAXA.CIS.UWOSH.EDU]
>Sent: Thursday, March 04, 2004 12:08 PM
>Subject: Re: [TAXACOM] Understanding evolution problems
>At 10:31 AM 3/4/04, Richard Zander wrote:
> >Nice point, but "our discipline"? "Systematics" is now phylogenetics and
> >its application to classification.
>I refuse to acknowledge *that* redefinition as well.

Pierre Deleporte
CNRS UMR 6552 - Station Biologique de Paimpont
F-35380 Paimpont   FRANCE
Téléphone : 02 99 61 81 66
Télécopie : 02 99 61 81 88

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