Selection and Population Regulation with Habitat Variation

Abstract

Sufficient conditions for protected polymorphism at an autosomal locus in a diploid organism are developed for a Levene model with explicit modeling of the population dynamics. Levene's condition for protected polymorphism, formulated in terms of weighted harmonic means of relative genotypic fitnesses, is only strictly valid for components of selection that are not immediately relevant for the regulation of the population size in the subpopulations. Global regulation of the population size produces Dempster's condition for protected polymorphism in terms of weighted arithmetic means of absolute genotypic fitnesses. The general condition for protection of an allele may be written in the same form as Levene's condition, but then the weights of the subpopulations depend on the fitnesses in the various habitats. The model allows for marginal habitats that cannot sustain a population if left isolated.