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Levings & Traniello — Territoriality in Ants 
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pheromones (Holldobler, 1974, 1976a; Traniello, 1980; Group III, 
Oster and Wilson, 1978). Thus both the track to the resource and 
the resource itself constitute the defended area. These foraging 
ranges are highly asymmetric — foragers from different colonies are 
only likely to interact when trail systems overlap. Essentially all 
foragers follow these trails in some species (Holldobler, 1976a), but 
this varies a great deal from group to group. In general, we expect 
that nest to nest distances will be shorter than the distance to the 
defended resource if colonies have highly skewed foraging. This 
prediction is born out in a study of three sympatric species of 
Pogonomyrmex (Holldobler, 1976a). Between nest distances are 
shorter in the two interspecifically defending species which forage 
on trunk trails than between nests of the individually foraging P. 
maricopa. 
3. Defense of area 
We consider defense of space larger in area than nest yards or 
core areas (Holldobler 1976a) to be true territoriality. This defense 
of area is, in essence, defense of potential foraging grounds. Only a 
few ant species, characterized by complex mechanisms of mass 
recruitment and high levels of intra- and interspecific aggression, are 
therefore truly territorial in our classification. Most dominant 
tropical canopy ants (some members of the genera Azteca, Oeco- 
phylla, Crematogaster, Camponotus, Monads, Polyrachis, Anoplo- 
lepis, Table 1) and at least one member of the genus Solenopsis are 
truly territorial. We must point out that in some cases the distinc- 
tion between true territoriality and resource defense is not perfectly 
clear, and that strategies of territorial defense and resource defense 
are at times difficult to distinguish. 
Solenopsis invicta, an introduced species from South America, 
has been extensively studied in the southern United States where it 
may form monocultures in fields (Wilson et al. 1972). Extensive 
mapping of one population showed overdispersion of nests main- 
tained over time despite frequent nest movement (Eisenberg 1972, 
Table 1). 
Maps of intercolony dispersion have been published for a number 
of ant species in tree crops in tropical areas (Table 1). Individual 
colonies hold territories in the canopy both intra- and interspecifi- 
cally. The distribution of the canopy mosaic of dominants can have 
a very complex structure (Way 1953; Greenslade 1971; Majer 
