Testing Relationships Between Biotic Components - Evolutionary Biogeography - page 174

Figure 5.5 Resolutions of a redundant distribution. (a) Taxon with a redundant dis-
tribution involving North America; (b-c) two possible solutions deleting one of the
distributions each time. AF, Africa; AUS, Australia; NA, North America; SA, South
America.
There is no special treatment for redundant distributions under assump-
tion 0, although Kluge (1988) proposed a weighting scheme in which a
smaller weight is given to the components involving redundant distributions.
Under assumption 1, it is interpreted that the redundant distributions are due
to duplicated patterns followed by extinction ( figs. 5.5b and 5.5c ) , where-
as assumption 2 adds the possibility that sympatry may be due to dispers-
al (Enghoff 1996; Page 1990a). Most of the authors prefer assumption 2 to
treat redundant distributions (Enghoff 1996; Morrone and Carpenter 1994;
Nelson and Platnick 1981; Page 1990a).
Missing Areas When no terminal taxon is distributed in one of the areas
analyzed, this area will not be represented in the taxon-area cladogram. In
the taxon (1 (2, 3)), if no species inhabits Africa (one of the study areas)
when the areas are replaced by the species of the cladogram, this area will
not appear in the taxon-area cladogram ( fig. 5.6a ) .
Missing areas, which are caused by extinction or insufficient studies,
are treated as noninformative. They are coded with “?” so that they can
be placed in all possible positions in the resolved area cladograms ( figs.
5.6b - 5.6f ) . Also, it is possible to treat them as primitively absent by coding
them with “0” (Kluge 1988).