POPULATION FLUIDITY IN LEPTOTHORAX 
LONGISPINOSUS (HYMENOPTERA:FORMICIDAE)* 
By Joan M. Herbers and Carol W. Tucker 
Department of Zoology, University of Vermont 
Burlington VT 05405 
Introduction 
Although social insect colonies are commonly conceived as stable 
entities in time and in space, considerable information exists to 
demonstrate that population fluidity can be pronounced. Data on 
ants show that workers can be exchanged between nests (Kan- 
nowski 1959; Scherba 1965; Chauvin and Leconte 1965; Alloway et 
al 1982; Del Rio Pesado and Alloway 1983; MacKay and MacKay 
1983); a colony can undergo budding (Scherba 1958; Talbot 1961; 
Brian 1965; Cherix et al 1980; Stuart 1985; Pamilo et al. 1985); and 
entire nests can move from one site to another (Van Pelt 1976; 
Smallwood and Culver 1979; Smallwood 1982; Droual 1984; 
Herbers 1985). These observations lead to the conclusion that in 
some species the colony is not a fixed entity, but rather a shifting 
collection influenced by ecological contingencies. 
That a given colony can occupy more than one physical nest site, 
a condition known as polydomy, deserves particular attention 
(Fletcher and Ross 1985). Evolutionary dynamics under conditions 
of colony fractionation are poorly understood, even though the 
consequences for eusocial evolution may be profound. There is sur- 
prisingly little information to document and measure the extent of 
population fluidity for any species, a gap we help to fill in this paper. 
Recent work demonstrates that some species of leptothoracine 
ants are polydomous (Alloway et al 1982; Del Rio Pesado and 
Alloway 1983; Stuart 1985). These inconspicuous temperate species 
are well-suited for detailed studies of polydomy because they are 
small and easy to culture. Here we quantify nest fission, fusion, 
migration, and other features of polydomy for Leptothorax longis- 
pinosus kept under semi-natural conditions in the laboratory. While 
* Manuscript received by the editor May 12, 1986 
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