Biogeography's aims

Alec McClay alec at ARC.AB.CA
Sun Apr 21 23:23:03 CDT 2002

On Fri, 19 Apr 2002 17:26:45 +1000, Robert Mesibov
<mesibov at SOUTHCOM.COM.AU> wrote:

 >More thoughtful biologists split biogeography into 'ecological
 >biogeography', dealing with distributions now and in the recent past, and
 >'historical biogeography', dealing with origins, extinctions, dispersal and
 >'connections' with long-term geological history. Ecological biogeography is
 >mostly pursued by ecologists. An example of their research would be
 >environmental-envelope modelling to predict ranges of single species, as
 >mentioned by Jim Croft here on TAXACOM a couple of days ago. Ecological
 >biogeographers regularly run up against distributions they can't explain
 >ecologically, and these are generally explained away as the result of
 >'historical contingency.'
 > [snip]
 >What's going on? We don't yet know, but the point is that Key's
 >single-taxon biogeography is unlikely to tell us. We'll need to use
 >molecular and other data from a whole range of taxa to work out a likely
 >history for (a) the two bits of Tasmania divided by the line and (b) the
 >taxa which respect that line in their distributions.
 >I don't think this example is atypical on a global scale. That's why I say
 >that biogeography's aim is to work out histories for 'inventories', not
 >single species. A hypothesised history for a single taxon may sound good
 >but be off the mark, because it doesn't embrace all the relevant
 >biogeographical information.

My original question was about whether it is possible to say anything with
a scientific basis about the origin or distribution of individual species,
i.e. why they live where they live, and how they got there, and whether it
is possible to identify their "centres of origin". I didn't mean to give
the impression that my main interest was in whether this question "belonged
to" ecology or biogeography, or in where to draw the boundaries between
various schools or subdisciplines. By all means, if looking at the whole
biota, or any other kind of evidence, allows us to make more reliable
inferences about this question, let's do it. But as a biocontrol worker,
it's still the single-species question "where did this species originate?"
that I need to answer. If it's possible to answer it by "embracing all the
relevant biogeographical information", I would certainly rather do that
than make do with a "hypothesised history".

Alec McClay
Research Scientist, Biological Control of Weeds

Alberta Research Council
PO Bag 4000, Vegreville, Alberta, CANADA T9C 1T4

Tel:    (780) 632-8207
Fax:    (780) 632-8612
Email:  alec at

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