ABSTRACT

I discuss phylogenetic relationships, nesting and feeding habits, kinship and ecological determinants of social behavior in the second largest taxon exhibiting eusociality, the termites. Contrary to previous hypotheses, cladistic analyses indicate that the woodroach Cryptocercus is probably not a sister taxon to the termites. Focusing on the reproductive consequences of termite societies, I place termite species along points on the spectrum of eusociality according to the reproductive potential of their offspring. The tendencies of workers to maintain their reproductive options in some species but not others are explained, in part, by termite nesting and feeding habits of four life types. Each life type is associated with a level of resource stability (nest and food resources) that sets the upper limit on the extent of worker altruism because resources influence maximum colony longevity. Cycles of inbreeding may yet be important in genera whose colonies are typically headed by sibling–mated supplemental reproductives. I discuss how reproductive–replacement strategies might minimize the effects of reduced genetic variability. Direct and indirect benefits explain why single–site and many multiple–site nesters provide alloparental care. Only indirect benefits, i.e. helping kin, appear to explain why centralsite nesters and numerous multiple–site nesters stay and help. I suggest that the cumulative indirect fitness benefits (the potential benefits over time) earned per altruist may best explain individual decisions in termites throughout the social spectrum.