Why is taxonomy placeless?

Curtis Clark jcclark at CSUPOMONA.EDU
Sun Feb 3 11:10:57 CST 2002

At 03:18 PM 1/31/02, Robert Mesibov wrote:
>Spatial locations, like morphological and molecular characters, are not
>randomly distributed in the world of Life. Yet locations, unlike other
>characters, aren't part of the input in analytical methods for guessing the
>Tree's structure. Why?

This is partly historical, but it is also part of a larger issue: if we use
a specific type of character to infer phylogeny, we can't use the resulting
phylogeny to study the evolution of that character, since the result would
be tautological. Biogeographers have been free to make all kinds of
inferences from phylogeny (let's not get started on *that* again :-)
because so little of it is constructed mainly on geographic characters.
Those of us who study morphology have in contrast waited for the current
"molecular revolution" to provide "morphology-free" cladograms against
which we can compare the features we study.

It seems clear that the cladogram most likely to reflect actual phylogeny
is the one that encompasses the greatest number of potential
synapomorphies, and there are methods to reduce circularity ("does the
cladogram look the same when I remove the feature I am studying",
generalized into a jackknife approach), but because few systematists are
good at everything, things get left out. I don't see any reason to ignore
geography a priori.

Curtis Clark                  http://www.csupomona.edu/~jcclark/
Biological Sciences Department             Voice: (909) 869-4062
California State Polytechnic University      FAX: (909) 869-4078
Pomona CA 91768-4032  USA                  jcclark at csupomona.edu

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