Immunity and mate choice: a new outlook

The notion that the immune system of potential mates can influence adaptive mating decisions is more than 25 years old and has sparked many fruitful investigations of mating behaviour and the fitness consequences of mate choice. Prior empirical work has focused on (1) assortative mating based on major histocompatibility complex alleles and (2) trade-offs between reproductive effort and immunocompetence that signal mate quality. These two approaches to understanding the link between immunity and mate choice have remained separate. Given that the immune system must flexibly respond to pathogens that an individual encounters over the course of a lifetime, it is important that researchers begin to incorporate both genetic and phenotypic indexes of immunity in studies of mate choice. Here, I outline several ways that investigators can begin to use a combination of immunogenetic and immunocompetence data to answer open questions about the influence of immunity on mate choice.