Genomic analysis of MHC-based mate choice in the monogamous California mouse

Genes of the Major Histocompatibility Complex (MHC) have been implicated in mate choice decisions in vertebrates. Theory predicts that individuals should prefer MHC-dissimilar mates. We show that in monogamous California mice, reproductive partners are not more dissimilar at MHC genes than randomly selected male-female pairs. Instead, our data suggest that pathogen exposure, not disassortative mating, underlies variability at MHC Class I and II genes in California mice.