Ridley's evolution book and panbiogeography

John Grehan jrg13 at PSU.EDU
Tue Sep 21 08:23:03 CDT 1999

Peter Hovenkamp wrote

>If you would please please stop using terms like "homology" in a
>biogeographic context, we might actually begin to understand what you mean...

The use of homology seems clear enough to me. Perhaps the term has
 not been used in biogeography much, and therefore is
confusing to biogeographers and systematists? If so, one could either
retract the term as suggested, or practioners will have to accomodate the
new perspective (as did systematists with cladistics). The concept
of homology is a major issue in biogeography since it refers to the criteria
by which any one distribution may or may not be said to be homologous
to another. This issue would seem to be inseparable from the construction
of biogeographic classifications that purport to represent something real
about the origin and evolution of distributions.

Naturally I regret that the meaning of what I say is obscure to some
biogeographers. I think this is an inevitable consequence of competing
research programs. However, I am willing, as above, to clarify my terms
and concepts as best I am able.

>I understand this to mean that Panbiogeography is the branch of
>evolutionary biology where geographic distribution is considered an
>inheritable character of organisms. Correct?

This model has been proposed by Russell Gray, and I am personally inclined
to agree under a broader concept of inheritance (i.e. beyond that limited
to genetic heritance.

John Grehan

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