[Taxacom] (neverending story)

[Richard Zander]

Some have questioned whether there is a metric for measuring degree of
difference, such as is often implied by the accursed paraphyleticists.
Since Linnaean classifications don't have much in the way of a built-in
metric (taxonomic distance at best as measured by distance on a page or
difference in and between ranks) one must refer to a cladogram or to a
diagnosis or discussion for either sister-group or ancestor-descendant
relationships. Polar bear white-furred, eats seals, .... A metric may be
an absolutely new feature.

Therefore, the question, I think, is a non-problem, since the details of
any different between taxa need to be looked for elsewhere. The metric
in classification is in the wording and indenting that signals
sister-group and ancestor-dependent relationships. Just because the same
metric possible as built into Linnaean classification must be used for
both phylogenetic and phyletic importance is a limitation of the
Linnaean system; fixing it should not involve elimination of a whole
area of evolutionary knowledge.

I also think the reason this is an "endless subject", a never-ending
discussion is because a new, good thing has become the be-all and
end-all of systematics, to the exclusion of much successful method.

*****************************
Richard H. Zander 
Voice: 314-577-0276
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/
and http://www.mobot.org/plantscience/bfna/bfnamenu.htm
Non-post deliveries to:
Missouri Botanical Garden, 4344 Shaw Blvd., St. Louis, MO 63110
*****************************


-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Frederick W
Schueler
Sent: Friday, April 03, 2009 11:29 AM
To: TAXACOM
Subject: Re: [Taxacom] (endless subject)

If "overall phenotypic similarity" could be recognized as a stand-in for
"ecological similarity," and could be measured on this basis, then
there'd be some way of meaningfully measuring and discussing the
phenomena that are now obliquely discussed under the heading of
paraphyly.

Linnean ranks could serve to express the chronological age of
holophyletic groups or to express "degree of difference," but if there's
no metric for measuring "difference" there's no way to discuss it.