Panbiogeography review by Cracraft

[John Grehan]

For those interested, Joel Cracraft presented a review of the
panbiogeography book in TREE 15(3) that deserves some comment. The review
was very interesting to read and is perhaps historically significant
because it seems to present two opposite views about panbiogeography. On
one hand Cracraft claims that the content of the book suffers from critical
problems such as the lack of cladistic criteria for testing and the lack of
space devoted to panbiogeographic method, the failure of the authors to
answer critics "adequately," and the "superficial attempt" to link
panbiogeography and conservation.

On the other hand "Panbiogeography" is a book that he would recommend to
all biogeographers interested in the interrelationship between geological
and biological history. He also concluded that the authors "forcefully
raise the important point that earth history and biotic history are deeply
interrelated and cannot be ignored." Cracraft did not, however, inform the
reader of the book's content that led him to such positive conclusions.

Cracraft's assertions notwithstanding, the book does contain many responses
to critics. The majority of responses are implicit as the authors agreed to
avoid polemics and concentrate on getting out a brief summary of the
important points and issues as we see them. This approach necessitated a
shift away from detailed technical debate (probably better allocated to
journal articles).

Cracraft assertion that the use of minimum spanning trees was introduced in
recent years is not quite correct. It is true that the concept was
articulated in recent years as characterizing tracks, but this was only
formalizing what Croizat was already doing most of the time (i.e. most of
Croizat's tracks conformed to minimal spanning tree). Similarly, his
assertion about the lack of cladistic criteria for testing is also
problematic. Since the baseline concept represents a unique spatial
homology, track congruence using spatial characters is "cladistic".
However, in the sense that panbiogeography uses spatial characters while
vicariance cladistics uses biological characters to assign biogeographic
homology, the absence of vicariance cladistic techniques in panbiogeography
simply  reflects a different methodology.

The review indicates that Cracraft may be of two minds about
panbiogeography, and that vicariance cladists, who in the past have been
among the strongest opponents of panbiogeography, are beginning to accept
that the method and synthesis does have general validity.

John Grehan