Biogeographic areas of Raven and Axelrod

John Grehan jrg13 at PSU.EDU
Tue Apr 20 21:28:36 CDT 1999

Some time ago a question was posted about whether panbiogeographic
methodology refuted the biogeographic areas or units of Raven and Axelrod
I've been distracted from commenting until now, but after re-reading their
paper on angiosperm biogeography and past continental movements I find
that they do not identify biogeographic regions in terms of natural
units. All they do is fit a series of biogeographic speculations onto the
drift theory of the time. They refer to taxa as being "Gondwanic" or "Laurasian"
for example, simply on the basis of the taxa having occupied, or presumed
to have
originated on, land that was part of such geological/geographic units, but they
do not establish that such areas constitute the biogeographic homology of such
groups in terms of a biogeographic analsysis.

I appreciate that there are probably not many systematists interested in the
principles of systematc classification applied to biogeographic homology, but
of those who do I would be interested in comments that can establish that
the biogeographic areas referred to by Raven and Axelrod (or even those of
Wallace) do conform to generally accepted principles of synapomorphy and

John Grehan

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