Islands, Science and Creationism

Jim Croft jrc at ANBG.GOV.AU
Thu Apr 18 07:43:17 CDT 2002


>As Curtis noted, and I agreed, context is critical.  Without an
>appropriate taxonomic, phylogenetic, or biogeographic context, my guess
>is that no one can tell me anything about the geographic history of the
>unknown plant in question (except for the trivial observation that it is
>found where it is).

The observation in itself may be trivial, but we can extract a climate (and
other environmental) profile for that record of occurrence and from this
predict where it could grow and then go out and test these hypotheses.  If
we had 2 or 20 independent occurrence observations our understanding of the
plants environmental envelope would be better, 200 or 2000 better
still.  Given the capacity of organisms to move from place to place, and
the very long time spans that have at their disposal to do this, it is not
surprising that these predictions work incredibly well - finding new
populations and range extensions on the basis of these predictions is now
fairly routine.

This seems pretty powerful to me.  I would hate to see current spatial
information about the taxon trivialized as I think it is perhaps the most
powerful tool we have to reconstruct biogeographic history.  In fact, it is
the only thing we can really nail down - whatever stories we make up have
to finish in that configuration.  It is the ground truth we are aiming
at...  :)

The intersection of this knowledge with quaternary and tertiary climatology
starts to paint a picture of where the plants could have been and probably
were, most likely an oscillating or pulsating mosaic in relation to climate
change.

[ As a digression, it has been said that certain groups of plants were
ubiquitous across the Australian continent, because they pop up in the
fossil record all over the place, and that the present day distribution is
simply a relictual result of the gradual drying out of the continent, but I
think statements like this need to be qualified.  Seen in the totality of
history they may have been growing all over the place, but at any one time
I bet they were not.  The knowledge of present day occurrence, and the
analysis of this environmental envelope, is one of the few tools we have to
tease out what may have happened. ]

jim

~ Jim Croft ~ jrc at anbg.gov.au ~ 02-62465500 ~ www.anbg.gov.au/jrc/ ~




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