Sexual Reproduction and Immunity

Abstract Sexual reproduction is a highly complicated process shaped in part by the need to optimise reproductive investment, which can differ and evolve antagonistically between the sexes. Sexual reproduction is also intimately linked with immunity through a variety of means. Combining these seemingly disparate biological functions has led to the emergence of the new field of reproductive immunity. One striking parallel between reproduction and immunity is the detection of ‘other’. Failure to detect pathogens results in disease. Failure to ignore self causes autoimmunity. Similarly, individuals, as well as gametes, must choose appropriate partners avoiding interspecific mating on one extreme or reproducing with kin to avoid inbreeding, on the other. The relationship between reproduction and immunity is likely affected by the mating system and the degree of sexual conflict. Reproduction and immunity seem connected in three ways by resource trade‐offs among life‐history traits, by disease reduction due to mate choice of healthy mates and protective genes for the offspring and by mating‐induced immunity to reduce infection risk. Key Concepts Mating and sexual reproduction can be linked to immunity in three ways: Reproduction and immunity can trade‐off. Choosing a healthy partner can result in protection for the actor and its offspring. Mating can directly result in immune responses. This immune activation may be a much older association between the immune system and sexual reproduction. Both immune activation and sexual reproduction involve recognising self from nonself. Immune responses upon mating can serve to protect females from infection and play a role in sperm selection. Mating system likely dictates the intensity and costs of these immune responses on mating.