Biogeographic units and classification

[P.Hovenkamp]

At 09:49 PM 25-04-99 -0400, John Grehan wrote:
>Regarding Hovenkamp's comments on the differences between
>biogeography and biological systematics, the problem that
>remains is the question of establishing natural classifications in
>biogeography.

No it is not - which was the point I was trying to get across. "Natural
classification" has no meaning in biogeography. In the absence of evolution
as we know it in systematics - if it's natural, it is not a classification,
and if it is a classification, it cannot be natural. Natural meaning here
"reflecting the generative process" (remember, in biogeography that is not
evolution AWKIIS).

>Regardless of the differences between biogeographic and biological
>processes, biogeographers are involved in the construction of
>biogeographic units and natural classifications.

>The way I look at the application of systematics to biogeography
>involves the question of natural units and natural classifications. In
>biological systematics the status of "natural" lies in a shared history
>(monpophyly) indicated by the presence of uniquely shared characters
>(synapomorphy). If biogeographic units and classifications are not to use
>these
>principles, what are the alternatives for establishing that a
>biogeographic unit is natural as opposed to arbitrary?

One alternative is, simply, not to expect biogeographic units to be
non-arbitrary. Arbitrary units may be very useful in a variety of contexts
- just as arbitrary classifications of biological objects are very useful
in many situations (root vegetables vs. leaf vegetables, fruits vs. nuts,
etc.).

Another is to accept my proposal not to use areas, but instead concentrate
on their boundaries, at least where these correspond to vicariance events
(as diagnosed by sister-group relationships).


P. Hovenkamp
Rijksherbarium, Leiden
The Netherlands
hovenkamp at rhbcml.leidenuniv.nl
http://rulrhb.leidenuniv.nl/