THE SELECTIVE ADVANTAGE OF FOUNDRESS ASSOCIATIONS IN POLISTES FUSCATUS (HYMENOPTERA: VESPIDAE): A FIELD STUDY OF THE EFFECTS OF PREDATION ON PRODUCTIVITY

Abstract

AbstractColonies of P. fuscatus that were initiated by various numbers of foundresses were studied to gather basic life table information. This information was used to estimate the selective advantage of foundress association according to a kin selection model, a parental manipulation model, two individual selection models, and a combined kin and individual selection model. Life table data were obtained for colonies located in exposed nest sites and for colonies located in nest sites provided with protection from vertebrate predators. Relative productivity of colonies produced by different size foundress associations and under different levels of predation pressure were determined. Multiple foundress colonies were found to be more productive and have an increased ability to re-establish after an episode of predation when compared with single foundress colonies. When predation levels on the colonies were high, multiple foundress colonies were more productive per colony and per foundress. When predation levels on the colonies were low, multiple foundress colonies were more productive per colony but less productive per foundress. At high levels of predation, when the queens and joiners were all assumed to have equivalent potential productivities, the kin selection model, the parental manipulation model, and the combined kin and individual selection model all predicted a selective advantage for joiners in foundress associations. At low levels of predation, when the wasps are assumed to have equivalent productivities, only the parental manipulation model predicted a selective advantage for joiners in foundress associations. When the assumption of equivalent potential is relaxed and when the wasps are assumed to be capable of detecting and acting upon individual differences in productivity, then all of the models could account for the existence of foundress associations. However, under this last set of assumptions the individual selection models require that the joiners have very low potential productivities.