1981] 
Levings & Tranie/lo — Territoriality in Ants 
275 
or congeners (Traniello, 1980). Inter-opening distances are not 
statistically different from 30 cm in a set of 12 nests with varying 
numbers of nest openings (P > 0.10, t test, 11/12 cases; range 2-27 
nest entrances), fitting our predictions quite well. The only nest with 
consistently closer inter-opening spacing was hemmed in by 3 larger 
nests; its openings occupied essentially the entire available area (18 
cm between entrances, 4 entrances). Although this species fits our 
predictions, we are unable to test them further with other species, 
either within species between nest openings or between separate 
nests. Nest entrance patterns of Paltothyreus tarsatus, which is also 
a polydomous species, appear to be similar in function to those of L. 
neoniger (Holldobler, personal communication). However, in poly- 
domous species of Camponotus, Atta and Pheidole, nest entrances 
are often much less than 2 r apart (Yasuno 1964a; Holldobler and 
Moglich 1980). Therefore, the association between foraging ecology 
and nest structure probably depends on the details of the biology of 
individual species. 
When resources persist for slightly longer time periods (patches 
that can be exploited in a few days such as rotting fruit), we also 
expect overdispersion of nests. This pattern has been confirmed in 
several species. Myrmecocystus mimicus nests in desert areas and 
exploits patchy, unpredictable concentrations of termites which 
form a major part of its diet (Table 1, Holldobler 1976b, 1979a, 
Holldobler and Lumsden 1980). During the retrieval of these 
patches of food, a nest will defend the area by engaging surrounding 
nests in a complex ritualized display and battle (“tournamenting”) 
which may result in the destruction of incipient colonies. Normally, 
the tournamenting behavior persists until the patch is exploited; 
searching in the area continues during this time. Nests are overdis- 
persed (G. Alpert, personal communication). Nests of Prenolepsis 
imparis are overdispersed (Table 1), and workers defend pieces of 
fruit for 1 or more days. This species has also been observed to 
tournament as Myrmecocystus mimicus does (Traniello, unpub- 
lished observations). It appears that in these species the cost of 
allocating a portion of the worker force to engage foragers from a 
neighboring nest in tournaments that prevent their access to a 
resource is less than the benefits obtained from these patchily 
distributed food sources (Holldobler and Lumsden 1980). 
b. persistent resources 
Persistent resources vary in their importance to colonies, depend- 
