Inter-nest Relationship in the Indonesian Ant, Myrmecina sp. A with some Considerations for the Evolution of Unicoloniality in Ants

Abstract

We studied the nest distribution pattern, the inter-nest relationship, and egg-laying ability of workers in the Indonesian myrmicine ant Myrmecina sp. A. This rare species has recently attracted biologists” attention by their peculiar symbiosis with a mite. The ant was locally quite dominant and occupied about 80% of the ant nests within a 10 × 10m-study plot on the floor of the secondary forest in the Botanical Garden of Bogor. We conclude that the local population of M. sp. A consisted of an unicolonial colony, because of the following three reasons: (1) they were usually tolerant to conspecific non-nestmates while showing strong aggression to the different species Tetramorium sp., (2) nests were contiguously rather than uniformly distributed, and (3) a mark-recapture experiment revealed that conspecific non-nestmates were easily incorporated into alien nests. This study reports the first discovery of unicoloniality in an ant species whose female reproductives are obligatory wingless ergatoid queens. Also unicoloniality in a forest dwelling ant in the tropics is unique. Workers can lay male destined eggs but they seem to lay only trophic eggs in the presence of the queen. We presented a hypothesis on the evolution of unicoloniality in this and other ant species with regard to the possible effects of genetic, ecological and historical factors. A population bottleneck following the introduction to a new habitat, policing and domination in the local habitat seem responsible for the evolution and maintenance of the unicoloniality.