natural units in biogeography

[P.Hovenkamp]

At 08:09 AM 27-04-99 -0400, John Grehan wrote:
>Peter Hovenkamp's assertion that  "Natural classification" has no meaning
>in biogeography represents a fundamental difference between our respective
>views.
>
>I agree that evolution of biogeographic histories is not the same thing
>as evolution of organisms, but I do not see that more than one context
>may be applied to evolution.
You can always use the word "evolution", or "evolve", like in "the
evolution of the stars", but that does not mean that that all evolving
histories are isomorphic in the sense of showing a pattern of nested
hierarchical relationships.

>Biota's have a history and a system of units
>and classification that reflects that history is, to my understanding,
>a natural classification. The units and classification tell us something
about
>the evolution of the real world.
Yes - but what exactly? If all stars are classified according to thier
observable properties, no doubt that some astronomer could apply a
clustering algorithm, and come up with a nested system of stars. Would that
tell us something about the way stars originated via splitting of one
primordial star? I think not.

>As mentioned in another posting, usefulness or utility is an arbitrary and
>artificial concept. In biology someone might find it useful to construct a
>classification
>in which bats and birds were grouped together. However useful, such a
>grouping would have little to do with origin and history (the natural
>character).
In very much the same way a grouping of areas in a nested hierarchic scheme
tells us very little about their origin and history.

>>Another is to accept my proposal not to use areas,
>
>I would agree with this since my position is that all area units are
>artificial.
>
>but instead concentrate
>>on their boundaries,
>
>If the areas are artificats so to are their boundaries.
Maybe yes, maybe no. I think the starting point for vicariance biogeography
is that if we see multiple sister-group relationships across a particular
line, we may be justified in thinking that that line is the location of a
vicariance event.


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