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[Vol. 88 
1976a,b). Individual colonies are clearly separated from each other, 
frequently by a no ant’s land between defended areas (Holldobler 
1979b). 
However, the statistical dispersion of these colonies is difficult to 
assess. Territory size varies a great deal between species because 
population structure has very strong effects on colony size and 
organization. Only a few polydomous, polygynous colonies may 
occupy extensive areas (Steyn 1954, Greenslade 1971, Leston 1973, 
Majer 1976a, b). The dispersion of volumes in space is difficult to 
treat statistically from published data although 3-dimensional meth- 
ods exist (Clark and Evans 1979, Simberloff 1979). Luckily, the 
biological evidence for dispersion and nonoverlap of area is over- 
whelming. Territorial battles are commonly observed and, in popu- 
lations followed over a number of years, control of a given area 
shifts from colony to colony and species to species. Although we 
predict statistical overdispersion, we are unable, for both statistical 
and biological reasons, to test for it in these cases. There is, 
however, no question about the existence of true territorial defense 
and the spatial separation of colonies. 
Ant plants are a special set of cases of true territoriality. Several 
tropical tree species (Table 1) are coevolved with certain species of 
ants (some members of the genera Pseudomyrmex, Azteca or 
Pachysima ) which protect the tree from herbivores or overgrowth in 
return for food and nest sites. Few other animals of any species are 
tolerated on the plant; the ant species are characteristically extreme- 
ly aggressive. The mutualism is sufficiently old than at least one 
species parasitizes it by using the plant without protecting it in 
return (Janzen 1975). These ant colonies are thus distributed with 
respect to the distribution of their host and form distinct territories 
within the canopy mosaic. They may also help “grow” new host 
plants by affecting the survival of nearby seedlings (Janzen 1967, 
1973). 
Intercolony Spacing Effects 
Interspecific overdispersion is regularly reported in almost all 
habitats (Table 1). However, detailed ecological studies indicate that 
different mechanisms operate in different habitats. In part, this is 
due to the fact that the only necessary characteristic required to 
generate overdispersed arrays is the ability of a colony to interfere 
