Biogeography and geological evidence etc.

P.Hovenkamp Hovenkamp at NHN.LEIDENUNIV.NL
Thu Feb 6 10:16:32 CST 2003


At 09:56 PM 2/4/03 +00-03, john grehan wrote:
>For my five cents worth (bit of inflation here) on Peter's thoughts:
That's not a bit - with 150% in just one day it is rampant hyperinflation.


>>Pondering these two quotations, it seems to me that Panbiogeography (if I
>>may take the utterances of John Grehan as statements of Panbiogeography) is
>>eager to have geology/tectonics informed by biogeography, but at the same
>>time prohibits biogeography to be informed by geology/tectonics.
>
>Maybe I can't win on this one - depending on how one may chose to apply
>terms and concepts.
There is always that issue, of course. In order to apply the same terms and
concepts as you do, I try to use literal quotations as a starting point.

>As far as geological theories about the past (the
>geo-historical narratives), I do not see them as informing biogeographic
>analysis since the narratives are simply conjectures that are the end
>product of geological analysis.
So here my interpretation seems to have been correct: biogeographic
analysis is not to be informed by the results of geological analysis.

>So in this respect biogeographic analysis
>is not 'informed' by geology/tectonics. When it comes to the method of
>spatial correlation between geographic patterns of biological distribution
>and geographic patterns of tectonics one might argue that biogeographic
>method is being informed by geology/tectonics since the geomorphological
>concepts of faults, suture zones, spreading ridges, former coastlines,
>escarpments, basins etc all have a historical meaning in geology. On the
>other hand, whatever these features may mean in geology they have an
>empirical presence in the present as observable features just as much as a
>distribution.
To talk about a "spreading ridges", "former coastlines" and at the same
time to deny the historical elements contained in these terms strikes me as
odd.
It never occurred to me before that Pan might be an approach directed at
avoiding all historical interpretations of our current observations - yet
this seems to be what John Grehan is driving at.

>>Now I can understand the feelings that drive this position, but I can't
>>see its
>>justification.
>
>In terms of Peter's interpretation neither can I.

Agreement at last!

>>If one allows the one to be informed by the other, one
>>assumes some sort of connection. Why then is it not allowed to use this
>>connection the other way?
>
>The example with the Galapagos was a biogeographic pattern as an empirical
>observation informing a geological conjecture. I would not see a
>biogeographic conjecture 'informing' a geological method any more than a
>geological conjecture 'informing' a biogeographic method.
Not informing a "method", but surely here a biogeographic pattern is
presented as informing an geological hypothesis about the history of these
islands.

>However, once a
>spatial correlation is proposed for a tectonic and biological pattern, it
>is possible to examine the historical context proposed for the geological
>feature - but that interpretation has no influence on the biogeographic
>method itself.
It does not have to influence the method - but all I ask is why it is so
vehemently denied that this historical context can ever be used to inform
the results of the biogeographic analysis in the same way that it is used
to help decide between alternative explanations of the geological observations?

>I doubt whether any of the above is really all that informative outside the
>context of actual applications of panbiogeography. Whether or not one may
>or may not inform the other at some level (such as background knowledge -
>see Craw and Weston 1984) is perhaps a matter for individuals to decide
>according to their taste.

Perhaps, but I see this as evasive. If we do science, we should,
occasionally, ponder the possibilities to justify the methods we are using.
Appeals to personal taste are poor justifications.

Peter Hovenkamp




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