New Zealand-Caribbean

[john Grehan]

TAXACOM at USOBI.ORG


At 09:28 PM 11/19/2002 +1300, you wrote:
> > I don't think it matters whether the comment was 'off the cuff' or not. The
> > statement showed that he was not familiar with standard biogeographic
> patterns,
>
>John Grehan reckons a NZ-Caribbean [actually Gulf of Mexico] pattern  "is
>not all that much of a curiosity as many taxa  [on land?] have representatives
>in the Western Pacific and the New World."  Assuming the pattern really
>exists for these marine creatures too I suppose we should be grateful he
>allows it is a little bit curious. There is only the inconvenience of that
>large
>chunk of land called the Americas in the way of  deepwater populations
>maintaining continuity.

Admittedly I take a liberty in interpreting the meaning of 'curious' in the
original article to refer to something that is puzzling and out of the
ordinary. At least that is the context for this term when used by Darwinian
biogeographers in general. I agree with Geoff that in geographic terms the
distribution is geographically incongruous - particularly if one takes
means of dispersal as being key to the geographic origin of taxa.

>My understanding is that the current distribution of organisms on earth, and
>in the sea, is the result of  a myriad of factors. Advancement of our
>knowledge of the events and influencing factors will gradually occur on a
>case by case basis with the application of improved techniques to gain new
>data.

Perhaps this is one area where Geoff and I take different perspectives.
Geoff looks to biogeographic knowledge on a case by case basis and new
data, whereas I look at biogeographic knowledge in the context of patterns
in general and applications of biogeographic method to current as well as
new data.

>The doctrinaire constructs of somebody's "standard biogeographic
>patterns" won't play much part in that process.

Perhaps that will depend on one's individual goals. I will not comment on
the 'doctrinaire' adjective as I do not know what this means with respect
to standard biogeographic patterns. No one has yet contested the existence
of the standard biogeographic patterns identified by Croizat even though it
would naturally represent a potential weak point in his research program.
Even Darwinian biogeographers (e.g. Blair Hedges) only contest the
historical events involved with the origin of the patterns, and vicariance
cladists who denounce the track method as an inferior method only end up
supporting the same tracks with their cladograms (Humphries et al on
Nothofagus and their parasites is a classic example)

>Sure there's room and a
>niche for people, the synthesizers, who enjoy  attempting  to reduce the real
>world to simple schemas, but others prefer to explore the many complexities
>of it all, and thus are willing to be uncertain of  explanations to fit
>cases until
>enough data is in.

This is an interesting summation on the current state of biogeographic
knowledge. One may chose between Geoff's position that biogeographic
knowledge comes from enough 'data' and the panbiogeographic position that
what one does with 'data' is just as important as the data itself. Croizat
did not have to wait for cladistics to be able to predict the composite
tectonic structure of the Americas and other areas (including hints in that
direction for New Zealand as long ago as 1952). Croizat did not have to
wait until geologists mapped the sea floor to predict the tectonic
significance of the Galapagos. In panbiogeography theory can, and has,
predicted the future discovery of 'new data'. The method, doctrinaire or
not in Geoff's view, does work.

John Grehan

John Grehan
Director of Science and Collections
Buffalo Museum of Science
1020 Humboldt Parkway
Buffalo, New York 14211-1293
Voice 716-896-5200 x372
Fax 716-897-6723
jgrehan at sciencebuff.org