1981] 
Levings & Traniello — Territoriality in Ants 
283 
which do not resist (seeds) are more likely to be size matched than 
items which require more complex treatment from the ants. Nests of 
specialist species may be restricted to areas which contain concen- 
tration of suitable prey (and as such violate the assumptions of our 
model). If resource size is matched with worker size class, then size 
polymorphism is one way to expand the resource spectrum of the 
colony without any changes in individual retrieval patterns (Oster 
and Wilson 1978). The development of coordinated retrieval mech- 
anisms can further expand the accessible resource spectrum. 
Almost all specialists, by definition, have less harvestable energy 
available to them than generalists. Thorne and Sebens (1981) 
suggest that species with low habitat quality (i.e., low food density) 
will have smaller nests than species with high quality areas (high 
food density). We extend this argument to predict that once a 
species has broadened its diet, it will include essentially all retriev- 
able food types encountered. Such an increase in diet breadth is 
needed to support large colony sizes, based on almost any simple 
foraging efficiency model. Although specific prey types, especially 
those with noxious chemical defenses, require special handling 
methods, many prey types may be captured and/or retrieved by 
species with a limited behavioral repertoire. Certainly scavenged 
material can be handled by all but the most specialized mandibular 
types. Since ant colonies persist over years, they more or less 
continually require resources. Resource distributions are highly 
variable over time; prey types appear and disappear seasonally 
(Mabelis 1979; Levings and Windsor 1982). It is a general con- 
sequence of this that once a species generalizes its diet, it is likely to 
overlap strongly with one or more sympatric species. The value of 
large colony size is reflected in reproductive output. Numbers of 
reproductives usually increase with colony size to some upper limit 
(Wilson 1971). Since the chance of success for any given reproduc- 
tive is low, high production will be likely to correlate with the largest 
probability of leaving successful offspring. Colonies which bud will 
tend to have higher rates of success if the new buds have large 
worker forces; this is also a function of energy intake. Colonies 
almost all require protein to raise brood (usually from insect prey or 
seeds) and many accept or require sugar to maintain adult workers 
(usually from Homoptera, fruit or nectaries). In general, large 
colony size is strongly associated with the maintenance of sugar 
