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cladobabble--here we go again
Jonathon Woolf wrote (11/14/97; 6:37a):
>OK, time for another of those stupid questions for which I am
>probably becoming infamous...
None of your questions are stupid. Any one who thinks they are should
re-evaluate his/her own attitudes. I hope there are always people around
who refuse to embrace new ideas until they have become old, tried and
true ideas (and maybe not even then). Our minds all work differently, and
such diversity can become the stuff of brilliance. Let's not put too
much "peer pressure" on conformity to ideas. Conformity to professional
standards, yes, but not to ideas.
>I don't understand why people got away from the plain old-fashioned
>idea of basing definitions on physiology: if X and Y have features
>1, 2, and 3 in common, then X and Y are in the same taxon. And taxa
>are defined as "the first organism to have features 1, 2, and 3, and
>all of its descendants." Tetrapoda then would be the first four-legged
>partially land-dwelling animal and all of its descendants. Amniota
>would be the first animal that laid hard-shelled eggs, and all of its
>Can anyone on the list explain this to me in words of ten syllables
Since the rise of phylogenetic taxonomy, we have changed the way taxa are
defined. That means that taxa are now different things from what they
used to be. Yet we still use the old names, as if we are referring to
the same kind of entity. But we aren't.
We have stem, node, and crown-based definitions, and there is no
unanimity on how a "traditional" term SHOULD be applied in phylogenetic
taxonomy. SHOULD "reptile" be stem-based, node-based, or crown-based, or
SHOULD there be three separate definitions? Who's going to decide, and
when, what we SHOULD do?
I see this as one of the flaws in phylogenetic taxonomy. There should be
only one way to define phylogenetic taxa. Forget the praticalities--I
know the reasons why these three approaches to definition have been
taken. Conceptually, the system of phylogenetic taxonomy is flawed in
that regard. All taxa should be defined in the same way so they are
comparable entities. (I admit, however, that I'd even settle for all
taxa within a phylum to be defined in the same way.)
As a teacher, my biggest problem is finding a way to be current, yet not
snow my audience of lay people under a blanket of undecipherable
cladobabble. The best approach seems to be to ignore the current
("proper"?) definitions for reptile and tetrapod, for example, and
explain what they are in the more traditional way. This makes sense to
everyone rather than just to the academic elite, the latter of whom seem
to enjoy arguing about how many angels with Greek and Latin names can
dance on the head of a pin. (Froth, froth, froth!)
Phylogenetic taxonomy has done some good things, but it has also created
a monster that did not exist previously and is taking a lot of time and
intellectual effort to tame.
For Jonathon's benefit, note that the longest word in the above has six
OK, everybody--I've put on my fireproof suit, and now it's your turn.
Norman R. King tel: (812) 464-1794
Department of Geosciences fax: (812) 464-1960
University of Southern Indiana
8600 University Blvd.
Evansville, IN 47712 e-mail: email@example.com