Geography Reference
In-Depth Information
as a progressive research program, being more like an adjunct to historical
geology.
Some cladistic biogeographers also criticized panbiogeography from the
methodological point of view (Platnick and Nelson 1988; Seberg 1986), in-
dicating that the procedure for orienting tracks is ambiguous because it
can take into account the minimum distance criterion or phylogenetic rela-
tionships. Tracks can also be oriented in agreement with main massings
(centers of numerical, genetic, or morphological richness), which resemble
the dispersalist criteria to determine centers of origin. Platnick and Nelson
(1988) distinguished Croizat's original ideas from those of his followers from
New Zealand, which they preferred to call “minimum-spanning tree biogeo-
graphy.” Its main characteristic is that it allows one to establish biogeograph-
ic relationships with little or no phylogenetic information on the taxa ana-
lyzed. It would allow a solution of biogeographic relationships based only
on geographic proximity, which would represent a shortcut that would avoid
the large amount of time cladistic analyses may take. Page (1987) justified
this procedure, arguing that considering the minimum distance between the
present localities does not imply assuming that evolution is parsimonious;
it is simply a methodological resource that can be applied in the absence
of other information for track construction. If there were cladistic informa-
tion that the closest geographic neighbor is not the next phylogenetic relat-
ive, then it would be necessary to consider the phylogenetic criterion. Page
(1987) also argued in favor of the use of minimum-spanning trees, indicat-
ing that they can be calculated exactly and efficiently. Platnick and Nelson
(1988) indicated that the ease of calculating them in itself is not a reason to
consider them a more appropriate tool. Joining the geographically nearest
localities could lead to erroneous conclusions when they belong to taxa that
were not also the nearest relatives or when the present geography is not the
same as that when they evolved.
Cladistic biogeographers have also criticized panbiogeography for using
phylogenetic information only to orient the individual tracks, which would
represent a partial application of Hennig's phylogenetic biogeography, which
supposes a priori that the most ancestral forms are situated in the center of
origin. Cladistic information is not used to reveal the relationships between
areas, which can be masked by present geography, so the construction of
tracks may reflect only present geographic proximity (Platnick and Nelson
1988). Craw (1982:305) had previously argued that there are “ample the-
oretical statements in Croizat's work demonstrating a keen appreciation of
