The evolution of habitat preference II. Evolutionary genetic stability under soft selection

A previous analysis of a single-locus, two-allele model of the evolution of habitat selection revealed that preference evolves toward equalization of parental investment in offspring placed in two different habitats in which population size is regulated independently (soft selection). That analysis is extended here to the case of a single locus with multiple alleles. The major result of this analysis is that regardless of how many alleles are present at equilibrium, new alleles will invade if and only if they tend to make parental investment in the two habitats more equal. In other words, the population evolves toward an Evolutionary Stable State (ESS) characterized by equalization of parental investment. The model may explain the maintenance of genetic variation for host (habitat) preference exhibited by many insect species.