The elusive paradox: owner--intruder roles, strategies, and outcomes in parasitoid contests

Models of dyadic contests for indivisible resources have predicted that the owner--intruder role distinction can suffice as a cue for evolutionarily stable resolution. This outcome may be "common sense" (prior owners retain the resource) or counterintuitively "paradoxical" (the intruder takes over), but the most recent models predict paradoxes to be an infrequent result, and there are also very few candidate examples provided by empirical study. Possible paradoxical outcomes were recently reported from the parasitoid wasp Goniozus legneri in which adult females compete directly for hosts. Here we provide further investigation, taking into account influences of contest ability (body size) and the value of the host to each contestant (correlated with the developmental stage of the owner's brood). We additionally evaluate contest strategies in terms of respect for ownership as evidenced by attack behavior during contests. Goniozus legneri shows weak, and thus only partial, respect for role asymmetries: such mixed strategies are predicted by recent models that assume population-level feedback on resource value parameters. Contest outcomes are influenced by asymmetries in resource value and body size and are generally common sense. Instances of paradoxical contests remain predictably elusive. Copyright 2009, Oxford University Press.