Fitness and Polymorphism for Net Fecundity Distribution in Iteroparous Populations

Numerical simulation showed that in environments which vary randomly in suitability for reproduction, populations polymorphic for net fecundity distribution may be superior in mean rate of increase and average population size to populations monomorphic for net fecundity distribution. Environments in which polymorphic populations are superior are similar to temperate-zone environments. Polymorphic populations are superior because they, uniquely, can change their net fecundity distribution in concert with changes in environmental suitability. Their net fecundity distributions and age distributions are usually congruent and their mean realized rates of increase are maximized.