INDUCIBLE DEFENSES AND THE ALLOCATION OF RESOURCES - A MINIMAL MODEL

We use dynamic-optimization models to assess the relative fitness consequences of inducible versus constitutive defense strategies. Our models assess the cost of defense in terms of reduced growth and reproduction of the defended organism. Resources are assumed to be allocated to growth, defense, or reproduction via a time- and state-dependent strategy that either does (in the inducible case) or does not (in the constitutive case) depend on the current predation threat. Inducible defenses are shown to be superior whenever predator attacks are unpredictable and sufficiently sustained (once initiated) for the defense to become effective. In the case of inducible defenses, the relative delays involved in switching among growth, reproduction, and defense are shown to be important determinants of the optimal allocation strategy.