The temperature independence of interaction strength in a sit-and-wait predator


  • Corresponding Editor: J. Drake.


The strength of interactions between consumers and their resources has important implications for the overall structure and function of food webs. These interactions can change with warming, depending on the foraging mode of the predator. Theory predicts that warming increases foraging velocity in ectotherms, but in a sit-and-wait predator that has zero velocity when foraging, the interaction strength should be temperature independent. Using the protist Urocentrum turbo and the sit-and-wait copepod Orthocyclops modestus, we tested this prediction by measuring dynamic interaction strengths (effect of a predator on prey population growth rate) and by estimating the parameters of a functional response. Both of these metrics were consistent with the prediction that interaction strength is temperature independent in a sit-and-wait predator. Our results indicate that there may be considerable variability in how warming alters foraging interactions, and estimating the overall effects of climate change on food webs may require consideration of the distribution of foraging strategies and the potential asymmetries that arise with interactions that involve different strategies.