Meeting Abstract

84.1  Friday, Jan. 7  Avian family dynamics and the evolution of virulence in parasitized nests HAUBER, ME; Hunter College of the City University of New York mark.hauber@hunter.cuny.edu

Obligate avian brood parasites exploit the parental investment of unrelated hosts, thereby reducing both the fitness value of current reproductive attempts and the future reproductive potential of foster parents. In turn, brood parasitic young are predicted to be selfish, and solicit maximal parental provisions without tolerating host nestmates. Yet, brood parasitic young display variable levels of virulence in the nest, ranging from nestmate-tolerant through -competitor to –evictor strategies. Here I evaluate the hypothesis that brood parasitic young face trade-offs between the costs of selfish behaviors to eliminate host nestlings and the benefits of co-habiting with several young in larger broods, using a general quantitative model of avian family dynamics involving competitive asymmetries of nestmates. In turn, experimental data between brood parasitic lineages with differently virulent strategies (e.g. Cuculus cuckoos vs. Molothrus cowbirds) and comparative data across differently vulnerable hosts of the same brood parasitic species (brown-headed cowbird: M. ater) both support predictions of the model and, overall, the trade-off hypothesis for the evolution of the virulence strategies of nestling avian brood parasites.