Communication in ants

social relationships or dominance styles to variation in food resource characteristics, such as the distribution, abundance and quality of food resources. If resources are of high quality and spatially clumped, for example, they are monopolizable by an individual, which usually leads to a dominance effect on food intake, because higher ranking individuals have preferred access. In this case, it will pay to be of high rank and maintain despotic dominance relationships. More egalitarian relationships are expected, for example, if low quality resources are more evenly scattered in the environment and hence fighting for access is not worth the effort. Given the lack of long-term field studies on macaque species — with only very few examples — a thorough test across species is still pending. An alternative model, the phylogenetic hypothesis, on the contrary proposes that the variation in social relationships is a consequence of phylogeny, with more closely related species showing more similar social patterns. So far, three broad species groups have been identified, the silenus-sylvanus group, which presumably is the oldest lineage, the sinica-arctoides group and the fascicularis group, which presumably includes all the nasty, despotic species. Cross-species comparison of captive macaques indeed shows evidence for conservative traits, such as rank acquisition or dominance relations between the sexes, which suggest at least some phylogenetic inertia. The possible influence of ecology, however, has not been tested in these studies on captive groups. So the debate continues.