Faith in parsimony

Robert Mesibov mesibov at SOUTHCOM.COM.AU
Wed Jul 27 18:33:37 CDT 2005

Many thanks for the references, Richard, I'll have a look. Maybe it wasn't
obvious, but I'm not actually all that interested in evolutionary
mechanisms. I do taxonomy and biogeography, not systematics, and I've been
trying to catch up on developments in cladistic and "probabilistic"
model-based methodology to see whether they might help me as a classifier
and landscape historian.

I've been particularly interested in molecular methodology because it seems
to me (as I've said before on Taxacom) that classification gets harder and
harder to do at higher and higher "magnifications" of biodiversity. I've
seen it so often in systematics papers: the basal splits show up in every
cladistic tree, but "support is weak" (or highly dependent on character
choice or weighting) for many of the finer branching patterns. The faithful
believe that if they only had more characters, all would be resolved clear
as crystal. IMHO, this is like turning up the volume on a poorly tuned radio
station. All that happens is that you hear the noise more clearly.

I've been thinking for years that with wide and intensive genetic sampling,
lots of distribution data and some independently supported hypotheses of
landscape evolution, it could be possible to build a classification of a
particular small group from individuals/populations up the hierarchy, rather
than down, and that a synthesis of this kind could also be read (by the
courageous) as close to the true and local evolutionary story. Note that I
don't have such a methodology; hence my curious rummaging through the
molecular "evolution" literature.

Unfortunately my area of interest is currently well populated by
phylogeographers, who worry me as much as strict cladists worry Ken Kinman.
Distance methods and oversimplified biogeographic models  -  ouch!
Dr Robert Mesibov
Honorary Research Associate, Queen Victoria Museum and Art Gallery
and School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 6437 1195

Tasmanian Multipedes
Spatial data basics for Tasmania

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