[Taxacom] Descent with differential modification
kennethkinman at webtv.net
Sat Mar 28 09:58:36 CDT 2009
I wonder how many taxonomists have read the 1998
paper by Eric B. Knox. He eloquently makes the same argument that Darwin
did, that although classifications should be primarily genealogical
(cladistically branching), that paraphyletic taxa are also sometimes
required due to what Darwin called "different degrees of modification".
Strict cladists who quote Darwin almost always omit this important
qualification. Anyway, if you don't have time to read the paper by Eric
Knox, I would strongly urge you to at least read the part of his
abstract given below. Especially note the phrase "strong paraphyletic
patterns of modification".
The use of hierarchies as organizational models in systematics.
by Eric B. Knox, 1998
Biol. J. Linn. Soc. London, 63(1):1-49.
Part of Abstract:
"Cladistics is monistic, with a singular focus on patterns of descent.
Descent has conceptual priority over modification, but the
organizational relationship is not exclusive. Cladistic classification
is an oxymoron because cladistics lacks the class concepts needed to
construct a classification, a point recognized by those who suggest
abandoning Linnaean classification in favour of a newly devised
monophyletic systematization. Cladistic analysis of descent can be
supplemented with an analysis of modification that provides the class
concepts needed to construct an evolutionary/phylogenetic
classification. When a strong monophyletic pattern of modification is
detected (in addition to its monophyletic pattern of descent), the
criterion of subsequent modification provides the basis for formally
recognizing a certain monophyletic group at a given rank, as opposed to
a group that is one node more inclusive or one node less. The criterion
of subsequent modification also permits detection of strong paraphyletic
patterns of modification, when they exist. By setting standards of
evidence needed to recognize paraphyletic groups, one concomitantly
strengthens the basis for formally recognizing selective monophyletic
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