Natural enemy specialization and the period of population cycles

P. Rohani*, H. J. Wearing, T. Cameron and S. M. Sait Institute of Ecology, University of Georgia, Athens, GA 30602, USA Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK Centre for Biodiversity & Conservation, School of Biology, University of Leeds, Leeds LS2 9JT, UK *Correspondence: E-mail: [email protected] Abstract The dynamical consequences of multiple-species interactions remain an elusive and fiercely debated topic. Recently, Murdoch and colleagues proposed a general rule for the dynamics of generalist natural enemies: when periodic, they exhibit single generation cycles (SGCs), similar to single species systems. This contrasts markedly with specialists, which tend to show classic (longer period) consumer–resource cycles. Using a wellstudied laboratory system, we show that this general rule is contradicted when we consider resource age-structure.