Recurrent evolution of dependent colony foundation across eusocial insects.

The spectacular success of eusocial insects can be attributed to their sophisticated cooperation, yet cooperation is conspicuously absent during colony foundation when queens are alone. Selection against this solitary stage has led to a dramatically different strategy in thousands of eusocial insect species in which colonies are started by groups of nestmates and the benefits of sociality are retained continuously. Dependent colony foundation (DCF) evolved recurrently multiple times across the ants, bees, and wasps, though its prevalence in termites remains unclear. We review adaptations at both the colony level (reproductive investment shifts from sexuals to workers) and the individual level (wingless queens evolve in ants), and other consequences for life history (invasiveness, parasite transmission). Although few studies have focused on DCF, the accumulated data from anecdotal reports, supported by indirect information including morphology, population genetics, and colony demographics, make it clear that this strategy is more diverse and widespread than is usually recognized.