Inter-Nest Interactions, Nest Autonomy, and Reproductive Specialization in an Australian Arid-Zone Ant, Rhytidoponera Sp. 12

Rhytidoponera sp. 12 ANIC is a large Australian ponerine ant which lacks a morphologically-differentiated queen caste. As is the case for many other Australian species in this genus, some of the workers mate and assume the egg-laying role. As has been inferred for species in the R. metallica complex (Haskins and Whelden, 1965) and observed for R. maniae (another large arid-zone species) and species in the R. impressa complex (Ward, 1981), colonyfounding under this life-pattern is probably usually accomplished by fission ("hesmosis"), in which one colony divides into two. Unlike the situation where nest-founding follows a dispersive mating flight, colony fission is likely to lead to the new nest being located close to the parent one, leading to a population structure in which neighboring nests are genetically related. A large study of the apportionment of genetic variation in a population of R. sp. 12 (Crozier et al., 1984) found that neighboring nests are indeed more similar genetically than expected by chancemthey are related. The finding (Crozier et al., 1984) that neighboring nests are related raises the question of colony boundaries. Does each nest represent a separate colony, or do daughter-nests remain socially connected after fission, forming polydomous (multinest) colonies? The two alternatives are not, of course, completely clear-cut, in that intermediates could occur between single-nest colonies and truly