Optimality models in behavioral biology

The action of natural selection results in organisms that are good at survi ving and reproducing. We show how this intuitive idea can be given a formal definition in terms of fitness and reproductive value. An optimal strategy maximizes fitness, and reproductive value provides a common currency for c omparing different actions. We provide a broad review of models and methods that have been used in this area, stressing the conceptual issues and expo sing the logic of evolutionary explanations.