Variation and Change in Behavioral Ecology

This paper argues for the importance of time in the behavioral ecology of changing environments; that is, how behavior changes in response to the time scale of environmental change. I distinguish between change, which occurs over time, and variation, which is measured instantaneously. Variation and change can be equated; this amounts to viewing a dynamical process as static. For example, a predator-prey oscillation involves changes, over time, in numbers of predators and prey. An atemporal measure of such changes might be the range of variation in population sizes, corresponding to the amplitude of the oscillation. Consideration of time scale tends to be submerged when variation is confounded with change. There are two reasons why time-dependent behavior merits further attention. First, it has important ecological consequences. Second, in the theory of evolution in changing environments, questions of the time scales of phenotypic and environmental change are crucial. But such questions have received less attention in behavioral ecology. A further emphasis on temporal factors is needed to link empirical, behavioral studies of changing environments with theoretical, evolutionary ones. After providing some definitions, to clarify what is meant here by time-dependent behavioral responses, variation, and change, I use some examples of the behavior of seed-eating ants to illustrate the ecological importance of time-dependent behavioral change. The following section reviews how current work on behavior in changing environments treats questions of variation and change, arguing that this work emphasizes instantaneous variation rather than temporal change. Finally, I consider how models of phenotypic response to changing environments, derived from other fields of evolutionary ecology, have explicitly considered temporal factors, and how these models might be extended to behavioral ecology.