Abstract
The fusion of behavioral ecology and ecology:- Behavioral ecology and ecology have projects in common. Community ecology can provide behavioral ecology with the tools to ask realistic questions about the current action of natural selection. Evolutionary ecology has moved beyond asking “Why does trait x contribute to reproductive success?” and on to “What are the conditions under which trait x contributes to reproductive success?” We need to bring this ecological perspective to the study of the evolution of behavior. Community ecologists have recognized that behavior influences ecological outcomes. For example, behavior contributes to the effect of history on community assembly, to indirect effects in predator–prey interactions, and to the responses of populations to human disturbance. More generally, behavior is often the source of context dependence; behavioral responses in different conditions lead to different ecological outcomes. As community ecology is broadening to include behavior, behavioral ecologists can begin to incorporate ecological perspectives in asking evolutionary questions.
Behavioral ecology and ecology need each other. Behavior is linked to ecology at every level, from the population to the ecosystem, but here I will focus on the relation of behavior to population and community ecology. Behavioral ecology joins the study of animal behavior to evolutionary biology; its goal is to explain how behavior determines fitness. The goal of ecology is to explain the outcomes of interactions of organisms with their environments, including other organisms. Ecology, especially community ecology, can provide behavioral ecology with the tools to ask realistic questions about the evolution of behavior. In turn, the study of behavior can help ecology deal with questions about context dependence.
ECOLOGY AND THE EVOLUTION OF BEHAVIOR
In the first half of the 20th century, studies of behavior and of ecology were more intertwined than they are now. It was taken for granted that an animal’s behavior could be understood only in the context of its natural history. To pursue evolutionary questions about behavior, we now need to bring back analytical natural history
Consider a 1938 study, published in the Journal of Mammalogy, which examines the feeding behavior, the construction of large mounds of twigs as nests, and the mating behavior of the dusky-footed wood rat in northern California.
The article is called “Biotic relations of the wood rat (Neotoma fuscipes) in the Berkeley hills,” and it lives up to its title, outlining the animal’s biotic relations by counting how many nests are near which plant species, how many sightings of the rats eating involve which food source, the distances among nests, and how these measures depend on season and habitat.
The early ethologists emphasized the importance of field observations like these, and even when ethology morphed into the field of animal behavior, with an increasing emphasis on physiology, no one questioned the value of learning about animals in their environments. But as we began to aim for generality, using experimental designs that permit statistical analysis, and as it became technically possible to learn more about the physiology of behavior, natural history lost its panache. Natural history was anecdotal; experiments were real science.
VARIATION
Behavioral ecology needs the perspective of evolutionary ecology to move beyond speculative accounts of what may have happened in the course of evolutionary history. Accounts that use current observations to reconstruct the past action of natural selection are always problematic. If anything back then was different from the way things are now, as it must have been, then even if a trait could have been the same back then, its ecological context was different. When it comes to behavioral traits, we cannot even tell how the trait was different back then, except by using comparative phylogenetic methods.
Behavioral ecology’s attitude to variation comes to it through its parent, ethology. The early ethologists were not much interested in characterizing the nature and magnitude of variation. Instead, the goal was to describe the stereotypic behavior characteristic of the whole species. For ethology, each individual represents its species. The individual, and by extension the species, has a fixed set of behaviors, and if you watch long enough, you will see all the behavior on the list.
CHANGE AND CONTEXT DEPENDENCE: WHY ECOLOGY NEEDS BEHAVIORAL ECOLOGY
Behavior is important for ecology because many ecological outcomes are the result of behavioral processes. The interactions of organisms and their environments arise from behavior. Behavior produces the predator–prey interaction: a predator catches, finds, and eats its prey and the prey avoids the predator, at least often enough to persist. To learn about this interaction, the ecologist samples numbers of predators and numbers of prey, so as to find the function that relates the 2 numbers, the functional response.
The numbers of predators and numbers of prey are the outcome of behavior, how the predators find their prey and how the prey hide or escape. Behavior produces mutualistic interactions. A colony of ants lives in a hollow domatium in the branch of a tree, eating the honeydew of scale insects that feed off the tree, and defending the tree from herbivores.
The numbers of predators and numbers of prey are the outcome of behavior, how the predators find their prey and how the prey hide or escape. Behavior produces mutualistic interactions. A colony of ants lives in a hollow domatium in the branch of a tree, eating the honeydew of scale insects that feed off the tree, and defending the tree from herbivores.