© 1996 by The Society for Integrative and Comparative Biology
Risk-Prone Behaviour Under Rules Which Have Evolved in a Changing Environment1
School of Mathematics, University of Bristol University Walk Bristol BS8 1TW, United Kingdom
This paper deals with risk sensitivity in amount of food, and is concerned with modelling the risk-sensitive behaviour exhibited by an animal which is attempting to survive a period such as winter. I argue that, in maximising survival probability, risk-averse behaviour is much more important than risk-prone behaviour. I also argue that animals in the laboratory will continue to use rules which are adapted to food sources which change over time. A model of environmental change is investigated. This model predicts that a consequence of change is that less riskprone behaviour than that predicted by standard models is to be expected in laboratory studies. The need to learn about a stochastic food source in a changing environment is predicted to further reduce the incidence of risk-prone behaviour. It is difficult to learn about highly variable food sources. This is shown to lead to risk-aversion even when the optimisation criterion is maximisation of mean long-term rate of food gain.
Implications of the general modelling philosophy are discussed.