Introduction

Ecological communities are complex networks of interacting species, and it has been a central challenge in community ecology to understand and predict their dynamics. To deal with this daunting complexity, scientists typically abstract these communities into more tractable subcomponents, such as food web modules (e.g., food chains, predator–prey interactions, competitive interactions) (Holt 1997), to elucidate the causal mechanisms that determine the dynamics of species interactions. However, even at this reduced level of complexity, researchers face the challenge of how much detail should be included to capture the full dynamics of natural communities without getting tangled up in details or losing generality.

Much of our conceptual foundation for species interactions is derived from basic models such as the Lotka–Volterra equations and extensions, which assume that per capita interaction strengths between species are on average the same across individuals within a population and that community dynamics are solely governed by changes in population densities. Similarly, food web theory traditionally treats a species as a single node in which all individuals within a species are expected to experience the same type and strength of species interactions (reviewed in Pascual and Dunne 2005; Montoya et al. 2006). While these assumptions make ecological systems much more tractable, they also sacrifice important biological details below the species level that may influence the dynamics of communities. In particular, by focusing on the species level we inherently assume that either all individuals within a population are identical, or at least, that they are on average the same and any variation around this mean does not alter the dynamics of the system and can safely be ignored. However, no population is truly homogenous and individuals within populations often vary considerably in their ecology. The question is: does this intraspecific variation matter?