Mutation and population size

Abstract

A combination of ecological and genetic models makes it possible to predict the effects of mutation on population size. Although all disadvantageous mutants produce the same genetic load (as conventionally defined) different types of mutants may have different effects upon the numerical equilibrium. Those reducing competitive ability can cause an increase in population size, despite the fact that they are eliminated by natural selection. When the selective values of genotypes depend upon their frequencies (or densities), conventional genetic load measures neither the effect of mutation on the rate of increase of the population nor its effect on the total numbers at equilibrium. If the consequences of mutation are to be adequately understood, the ecological parameters must be taken into consideration. © 1973 The Genetical Society of Great Britain.