Time-energy budgets and optimization

Summary

Since the process of natural selection entails a comparison of phenotypes and choosing of the best, optimality theory appears appropriate to identify selection pressures. Optimality theory doesnot test whether an organism is designed optimally — it assumes it. The ingredients of a complete optimization model are outlined and two approaches are exemplified. Both time-energy-budgeting and Pontryagin's maximum principle lead to semi-quantitative predictions about, e.g., an animal's behavior; they merely entail an inequality formalism. A discrepancy between prediction and test would not yet show a behavior to be maladaptive since several other explanations are possible. Animals optimize their behavior over intervals ranging from less than a second to months or years. It is unknown whether, with a long interval, the animal makes use of the opportunity to revise its decision(s). Present optimal foraging models predicting, e.g., diet breadth are too simple in that foragers a) may not always maximize energy intake, as postulated, b) have to allow for nutrient, toxin and remedial content of food items, and/or c) have to allow for interaction of items, annihilating their ranking along a unidimensional scale of profitability.