Agonistic Interactions and Reproductive Dominance in Pachycondyla Obscuricornis (Hymenoptera: Formicidae)

In many animals, agonistic interactions among members of a social group have been demonstrated to be associated with the formation of dominance hierarchies, which result in a reproductive rank order within the group. This type of social structure has been shown to occur in both vertebrate and invertebrate taxa, and the general pattern observed consists of one or a few highly-ranked individuals being responsible for most of the reproductive activity within the group (Wilson 1975a). Dominance orders leading to differential reproduction by colony members have already been documented for bees, wasps and ants (e-g., Pardi 1948, West-Eberhard 1969, Brothers and Michener 1974, Cole 1981, Franks and Scovell 1983, Bourke 1988, Heinze and Smith 1990, Roseler 1991). In more advanced ant societies, the morphologically differentiated queen usually holds her top position in the reproductive rank order of the colony by means of inhibiting pheromones which suppress the reproductive activity of workers (Fletcher and Ross 1985, Wheeler 1986). However, in phylogenetically more primitive ant species in which the queen and worker castes are often poorly differentiated, or in which the morphological queen caste has even disappeared entirely and reproduction is performed by mated workers (gamergates), the behavioral mechanisms regulating reproduction within the colony are complex and variable (Peeters 1987, Fukumoto et a1 1989,