[Taxacom] Rational holophyly and deological extinction
Richard.Zander at mobot.org
Mon Mar 16 13:50:06 CDT 2009
I think there is a rational (sort of) justification for using holophyly
in classification. It goes this way:
Science is to religion as phylogenetic analysis is to
Science cannot deal with religion because religion is not amenable to
the methods of science. Religion is commonly accused of being
"intuitive" or a bunch of attractive "stories."
Phylogenetics cannot deal with ancestor-descendant relationships because
the methods are solely analytic of sister-group relationships.
Ancestor-descendant relationships are commonly found as products of
alpha taxonomy, and are commonly accused of being "intuitive" or a bunch
of attractive "stories."
Intuition in science is of great pragmatic value when combined with data
and a research program, while humankind is glorified by its
story-telling abilities, e.g. informed hypotheses about nature that may
A goodly portion of evolutionary knowledge concerns ancestor-descendant
relationships, and eliminating their refection in classification
cripples both systematics and any field dependant on classification,
such as evolution, ecology, biodiversity, biogeography, paleontology,
and so on.
Forcing classification to reflect only the sister-group conclusions of
phylogenetic analysis is an ideology, and like all ideologies (see
Wikipedia) is a comprehensive vision, being logically consistent within
a narrow and limited range of data about nature, reflecting an excessive
need for apparent certitude and infallibility, is a relativistic
intellectual strategy for categorizing the world, and is "normative" of
group interactions (everybody agrees on a new paradigm). It certainly
simplifies classification, but at what expense?
Ideological extinction is the fate of autophyletic (descendant groups
recognized at same taxonomic level as ancestor) taxa, and of
paraphyletic taxa split into non-recognition. Although taxa of high
visibility (Aves, polar bears) seem immune to ideological extinction,
many groups simply disappear from classification because they were
embedded in an ancestral group of the same rank. In my own field,
bryology, three families (Ephemeraceae, Cinclidotaceae, and
Splachnobryaceae) have been sunk in a recent influential phylogenetic
classification into one larger one (Pottiaceae) without discussion
because they were autophyletic in previously published molecular trees;
their names do not appear anywhere in the classification, which offers
If absent, then the descriptions of their evolutionary novelty will also
be absent in future taxonomic studies (family synonyms of families do
not usually have descriptions) and the families will not be discussed in
the future in other fields relying on the expertise of such taxonomic
studies. In my opinion, this excision of a whole class of evolutionary
knowledge (ancestor-descendant relationships) from classification is
It may be true that
Science : religion :: phylogenetics : ancestor-descendant relationships
But then, this only reflects that phylogenetics is valuable for
ascertaining sister-group relationships, but other methods must be used
for determining ancestor-descendant relationships. Such methods do exist
and their results should be part of classification.
Richard H. Zander
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/
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Thomas G.
Sent: Monday, March 16, 2009 12:37 PM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Reptilia (and Hominidae)
At 10:12 AM 3/16/2009, Kenneth Kinman wrote:
>If strict cladifications tend to be more destabilizing and sometimes
even less informative, why continue doing it just because of some
arbitrary rule against paraphyletic taxa?
Key word: "arbitrary." I do not buy that "non-informative"
mumbo-jumbo. The decision to enforce holophyly as the only sort of
monophyly seems to me to be a fiat a priori with no rational
Thomas G. Lammers
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