| Abstract: | The effects of variations in population size may be importantin the evolution of individual behavior. We use simulation modelsto study the stochastic evolutionary contest between two behavioralstrategies affecting individual survival and reproduction, oneconservative (low fecundity and low mortality risk), the otherrisky (high fecundity and high mortality risk). Trade-offs ofthis kind are involved in many types of behavior, includingforaging under risk of predation, parental care, size versusnumber of offspring, and so on. We treat the combined effectsof demographic and environmental variance, demographic variancebeing important for small populations and environmental variancebeing important at all population levels. With high environmentalvariance, population numbers fluctuate sharply, so that demographicvariance becomes intermittently important. As a consequence,either behavioral morph may become fixed in the population,depending on initial conditions and on chance events. We treatboth phenotypic and genetic models. In a genetic model withthe heterozygote employing the risky strategy, both behavioralmorphs may coexist as a randomly fluctuating polymorphism. |
