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Platnick 1981), whereas dispersal and distributional patterns (Halffter 1978,
1987) are similar to cenocrons. Biotic elements, defined as groups of taxa
whose ranges are significantly more similar to each other than those of
taxa of other such groups (Hausdorf 2002; Hausdorf and Hennig 2007), and
chorotypes, defined as sets of species with a coincidence in their spatial dis-
tribution that is greater than expected at random (Báez et al. 2004; Baroni-
Urbani et al. 1978; Gómez-González et al. 2004; Zunino 2005), represent
interesting concepts. Although they seem to correspond to biotic compon-
ents, I find that they may help identify cenocrons because they may allow
identification of biotic units even when substantial dispersal affected the dis-
tributions of the taxa analyzed.
Predictions are not usually formulated in evolutionary biogeography be-
cause, like other historical disciplines such as systematics, paleontology, or
geology, evolutionary biogeography studies unique events that occurred in
the past (Mahner and Bunge 1997). Alternatively, we may use biogeograph-
ic patterns to make retrodictions, that is, to “predict” past events (Morrone
1997, 2004a). For example, if a panbiogeographic analysis led one to identi-
fy an area as a node or a cladistic biogeographic analysis showed an area
with conflicting relationships with other areas, one can infer that such area
is composite or “hybrid” from a tectonic viewpoint. The geological analysis
of such an area may allow one to falsify our retrodiction.
