Debunking the myth of termite pleometrosis: Costs and (few) benefits of group foundation in Nasutitermes corniger

Colony foundation in most termites is strictly monogamous, but in a few species, colonies are headed by unrelated primary reproductives. Although pleometrosis has been widely accepted as a strategy by which mature N. corniger colonies become established in nature, no research has ever focused on colony establishment, the appropriate stage of colony development, to address whether pleometrosis is indeed a common phenomenon. A cost/benefit analysis tracked the survival and reproduction of 5000 laboratory-established incipient colonies of the facultatively polygamous neotropical termite N. corniger. Pleometrotic incipient colonies experienced higher failure rates than monogamous pairs and 99% lost at least one founding member. Although oviposition commenced earlier in larger founding groups, these colonies required more time to produce workers and soldiers than pairs. The size of surviving colonies 90 days post-establishment was equivalent regardless of their original breeding strategy.  Additional mate choice experiments tested the role that intrinsic (i.e. genetic) and extrinsic (i.e. environmental) factors play in fostering pleometrosis. Through microcosm and mesocosm experiments, we manipulated nest site availability, abundance of potential mates, and parental colony on founding group size.  While the first two factors did not impact group size decisions, alates from specific parental colonies were more likely to establish and maintain colonies in larger founding groups. Hence, tendencies towards pleometrosis appear to have a genetic component.  Given the significant costs of pleometrosis, we suggest that polygyny in mature colonies is actually achieved through the merger of young colonies, rather than pleometrosis.