Mate choice or polyandry: reconciling genetic compatibility and good genes sexual selection

Abstract

Sexual selection for good genes is based on the assumption that ‘good genes’ are equally good for all females. In contrast, selection for genetic compatibility is based on the assumption that offspring viability will depend on the interaction between male and female genotypes, and hence one male may not be good for all females. Here we present a simple model to examine the relationship between the genetic compatibility hypothesis and good genes sexual selection. We examine the circumstances under which selection arising from genetic compatibility will favour an increase in the number of males a female mates with. Our model shows that if there is some cost of mating, then some form of sperm selection based on compatibility is essential for the evolution of polyandry for compatibility. Furthermore, we found that when both good genes and compatibility selection are in operation, selection for compatibility can reduce directional sexual selection by causing females to mate with males of lower genetic quality.