Sex-specific mate choice and mate change based on MHC-IIB dissimilarity in a genetically monogamous seabird

Among species reproducing sexually, mating strategies represent a major component of individual fitness. The Major Histocompatibility Complex (MHC) is an extremely diverse set of genes responsible for immunological recognition and defense against pathogens. Although MHC-dissimilarity between mates has been proposed to drive mate choice through increased offspring pathogen resistance, evidence is mixed, and evidence for other MHC-based mating strategies remains rare. We investigated whether MHC-IIB dissimilarity is associated with mate choice and mate change in the genetically monogamous black-legged kittiwake ( Rissa tridactyla ). We found that first-time male breeders are paired with females more MHC-IIB dissimilar to them than expected by chance. After a successful reproduction, the more males are MHC-IIB dissimilar to their mate, the less likely they are to change mate. When males change their mate, they tend to be more MHC-IIB dissimilar to the new mate compared to the previous mate. However, males are not more MHC-IIB dissimilar to their new mate than expected by chance. We did not find evidence for an effect of MHC-IIB dissimilarity on mating strategies when considering the female’s perspective. Male mate choice should not be overlooked in species with bi-parental care in which the male performs a significant part of parental care.