Is biogeography science?

John R. Grehan jrg13 at PSU.EDU
Fri Apr 26 11:35:02 CDT 2002

Peter Hovenkamp wrote:

>One of the things a hierarchical scheme does is to specify a relative order
>of the splitting events   - something a panbiogeographical analysis, as far
>as I can see, will never do.

Panbiogeographic analysis is certainly not phylogeny construction using
biological characters although it can contribute spatial hypotheses of
relationship that can be compared with predictions of relationship based on
biological characters

>It is not too dificult to see this
>specification of relative temporal order a "historical prediction".

Agreed, but the information is only temporal - not spatial. Panbigoeography
provides criteria for specifying the spatial connection between related
taxa. At present it seems to me that spatial connections made in other
biogeographic approaches are conjectural based on a presumed geological
history. For example, in a study of carabid beetles Leibherr produced a
cladogram for the Caelostomini which he overlaid onto the geographic
distribution with the phylogenetic links drawn across the Atlantic to
connect the American and African relatives. However, there were no criteria
given for making this spatial connection. After some correspondence I found
out that it was based on the continental drift model as providing a
geological mechanism for the disjunction. Thus the choice for spatial
connection was made according to be belief that the American-African
disjunction was due to the opening of the Atlantic rather than any data
from his 'biogeographic' analysis. As it happens, in terms of track
construction I would agree with his choice. Whether or not one agrees with
my rendition anyone interested can see the example at

In terms of baseline homology the Caelostomini share something more in
common with the ground beetle genus Tachyla than to the Pacific based Broscini.

John Grehan

>Note that this statement uses the much laxer "in the light of" - suggesting
>that any approach that even dares look to other sciences is itself not
>I'm glad that that, at least, seems not to have been John Grehan's intention.

Correct. My intention was to draw attention to biogeography that relies on
other sciences to reconstruct the past being uninformative with respect to
biogeographic method. It would be like geology obtaining geological
patterns and then looking to biogeographic analysis of biological
distributions to reconstruct the past and fitting the geological narrative
to fit in with the biogeographic narrative. As for whether biogeography
that derives the totality of its historical reconstruction from other
sciences is science or not I will leave for others to judge.

John Grehan

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

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