Parasite infections affect males and females differently across a wide range of species, often due to differences in immune responses. Generally, females tend to have stronger immune defences and lower parasite loads than males. The major histocompatibility complex (MHC) plays a crucial role in the adaptive immune response, and extensive research has explored how variation in this region influences infection and fitness outcom...

Immune defence is a key component of fitness, and individuals are expected to have evolved preferences for mates that ensure immunocompetent offspring. Potential preferences include those for mates with specific heritable immune gene profiles (“good genes”) or for immunogenetically dissimilar mates to increase offspring immune gene diversity. The major histocompatibility complex (MHC) is by far the most investigated immune gen...