Smart vs. wise systematists

[Robert Mesibov]

for John Grehan, mainly:

Humphries, C.J. 2004. From dispersal to geographic congruence: comments on
cladistic biogeography in the twentieth century. Pp. 225-260 in Williams,
D.M. & Forey, P.L., Milestones in Systematics. The Systematics Association
Special Volume Series 67. Boca Raton: CRC Press; 290 pp.; ISBN
0-415-28032-X.

IMO this clearly-written essay is a fair treatment of the development and
uses of all current methods, although panbiogeography isn't Humphries'
favourite. He believes it's possible to establish area homologies akin to
biological homologies. He thinks the best way to discover area homologies is
through cladistic analysis of taxa living in those areas. He stresses that
cladistic methods used in this way will only _classify_ areas.

It's not exactly clear where you go from there. "Natural" biological
classification is hierarchical because descent is hierarchical. In what
sense could an area classification be hierarchical? How exactly do you
define the historical relationships between areas independently of the
historical relationships of their taxa? Anyway, why do it? Which would be a
more interesting history of India: one that recounts the rich cultural pasts
of its component areas and peoples, or one that says the overwhelmingly
important historical fact is that India is a former colony of Britain
(political child-parent relationship), or that the principal languages
evolved from a particular linguistic stem (linguistic child-parent
relationships)?

The following is worth quoting from Humphries' closing remarks:

"I believe that although there is still a very long way to go in uncovering
biogeographic patterns, there is just one underlying sequence of
geographical and geological evolution. When this is adequately investigated
it will explain most, if not all, the large-scale distribution patterns.
Critical changes in biogeographic methodology suggest that the underlying
theory of change will be based on an exhaustive analysis of biological and
geological cladograms ([refs]). This would be more satisfying than a
continuous outpouring of individual stories for every group of organisms and
techniques for overcoming the need for taxic homology."

If you read my post of a couple of days ago you'll know how violently I
disagree with that last sentence. Top-down understanding of general patterns
might be more satisfying to Humphries, but it doesn't throw so much as a
firefly flash onto the dark histories of individual taxa and individual
areas. I'd prefer to see biogeography built from bottom up in future, with
plausible "individual stories" of small areas and small taxa steadily
accumulating to suggest patterns at larger taxonomic and spatial scales. The
"continuous outpouring" that Humphries disdains hasn't happened yet. Instead
we have learned, decades-long debates about, for example, the taxon
Nothofagus and the break-up of Gondwana, with methodological partisan
sniping. I'm pleased to hear that local-scale phylogeographic studies of
individual Nothofagus species have begun. That's real progress.
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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
http://www.qvmag.tas.gov.au/zoology/multipedes/mulintro.html
Spatial data basics for Tasmania
http://www.geog.utas.edu.au/censis/locations/index.html
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