DIET OPTIMIZATION WITH A NUTRIENT OR TOXIN CONSTRAINT

The diet optimization model with nutrient constraints proposed by Pull iam and a similar model with a toxin constraint by Stephens and Krebs are not properly formulated. The appropriate version of the model is f ormulated and solved for the optimal diet. The model reveals that part ial preference could occur only for one prey type, while all other pre y types follow the zero-one rule. The model also indicates that the pr ey selection criterion changes as the intensity of the constraint is c hanged, so that we cannot rank prey types. The solution of the model f or the two-prey-type case shows different qualitative predictions from those of Pulliam and of Stephens and Krebs. (C) 1995 Academic Press, Inc.