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agent of evolutionary change. Croizat's ideas suggest the possibility of
a new, more integral evolutionary synthesis (Colacino and Grehan 2003;
Grehan 2001c; Llorente Bousquets et al. 2000; Morrone 2000c, 2000g).
Through panbiogeography (Croizat 1952, 1958b, 1964, 1976)—and espe-
cially after its “hybridization” with Hennigian phylogenetic systematics to ori-
ginate cladistic biogeography (Nelson and Platnick 1981)—he contributed
significantly to the development of a new biogeographic approach.
Croizat developed his panbiogeographic approach to test classic disper-
salism by comparing hundreds of plant and animal distributions, trying to de-
terminewhethertheyagreewiththeexpectationofchancedispersalaccord-
ing to their particular dispersal abilities. Croizat found a limited number of re-
petitive distributional patterns or generalized tracks, which had little relation
to present-day geography and comprised taxa with very different means of
dispersal. This finding is contrary to what one might expect—a chaos of con-
flicting distributions—from the dispersal model. Panbiogeography assumes
that geographic barriers evolve along with biotas, or “life and earth evolve
together” (Croizat 1964:iv). When Croizat (1958b) tried to associate the dis-
tributional patterns with geological events, he found that Wegener's theory
was insufficient with respect to the sequence of geological events, espe-
cially for explaining complex biogeographic patterns in the areas bordering
the Pacific Ocean. For this reason, he thought that Wegener's theory might
explain old (pre-Permian) patterns satisfactorily, but it was incongruous with
most modern patterns, so he rejected it, choosing to arrive at his own con-
clusions in light of the observation of the distribution patterns.
In
Space, Time, Form: The Biological Synthesis,
Croizat provided some
precision for his panbiogeographic method, which consists of “finding out
what nature herself tells of it all when speaking through strictly factual
scores” (Croizat 1964:iii). The analytical tool Croizat chose was the con-
struction of tracks, the “graphs of geographic distribution” or the “primary co-
ordinates” that “open the way to an enquiry into factors of
time
and
form
ma-
terial to our considerations on
space
” (Croizat 1964:7). By comparing these
tracks it is possible to discover patterns, which elucidate both morphologic-
al differentiation (“form making”) and translation in space. In a diagram (
fig.
uted in an area although differentiated in subordinated taxa, such as sub-
species or races (a and b), and how mountains, lakes, and volcanoes arise
andfragmenttheoriginaldistribution,inducingthedifferentiationofnewspe-
cies. This process involves two different stages: immobilism, which is re-
