Preweaning experience in the control of mating preferences by genes in the major histocompatibility complex of the mouse

The major histocompatibility complex (MHC) of genes of the mouse influences mate choice. Typically, inbred males prefer to mate with females that differ from themselves at this gene complex. Previous studies documenting differences between mating preferences of inbred and F2-generation males, as well as a possible effect of ambient mouse odors on preference, indirectly implicate rearing history as an influence in the determination of mating preference according to MHC types. To test directly the role of rearing history, entire litters were fostered onto parents of the same or different MHC types. Fostering of males onto parents of different MHC types reversed the natural preference; under these conditions, matings with females of the same MHC type as the fostered male were more frequent. Thus, male mating bias appears to be acquired during early development through exposure to parental MHC-controlled signals. Preliminary studies of mating biases in fostered females demonstrated a mating bias that was unaffected by fostering experiences. These studies indicate that the same set of genes involved in regulation of immune function also determines, in part, mate choice. A male bias in favor of females whose MHC types differ from the male's parental MHC types could serve to promote heterozygosity at the MHC.