Biogeographic memory

[John R. Grehan]

>May I interject something here from left field?  I agree that
>biogeographic analysis probably is not to be informed by phylogenetic
>analysis based on other characters, but what about the opposite?  I do
>believe that phylogenetic analysis can be informed by biogeographic
>considerations, if paleoclimates as well as present climates can be
>determined with reasonable certainty.  What do you think about this?
>
>Steve

Thanks for the pertinent observations. I don't know if you have seen the
panbiogeography book, but it more or less outlines my position on the
relationship between phylogeny and biogeography. Phylogenetic analysis is
necessary to postulate a particular biological relationship that can be
submitted to biogeographic analysis. The latter is independent if there is
an independent criterion for relationship. In panbiogeography that
criterion is spatial homology. One may reassess the biological
relationships according to their spatial relationships through criteria
such as common baseline, spatial geometry, main massings etc. Any of these
spatial characters may lead one to reassess the biological hypothesis, just
as the biological hypothesis itself introduces constraints on the spatial
analysis in the first place. Some such as some cladists would view this as
circular whereas I look at it as reciprocal illumination.

If you introduce other issues such as paleoclimatic considerations what one
is doing is taking a biological pattern of relationships and assessing it
in some way by its relationship to a historical model which is only a
theory about the past. The critical issue is how does one link the
biological pattern to a particular historical event hypothesized to occur?
In most cases biogeographers just assert that there is a link.

I'm not sure if that sheds much light on the matter.


John Grehan
Frost Entomological Museum
Pennsylvania State University
Department of Entomology
501 ASI Building
University Park, PA 16802. USA.

Phone: (814) 863-2865
Fax: (814) 865-3048

Frost Museum
http://www.ento.psu.edu/home/Frost/index.html