Use of the MHC for mate choice in wild house mice (Mus domesticus).

The mechanisms maintaining natural diversity at the major histocompatibility complex (MHC) are not well understood. To increase knowledge of one potential mechanism, I examined the use of MHC genes for mate choice by wild house mice in a controlled laboratory setting. Three rearing groups of wild test mice were produced: non-fostered control mice, mice fostered into families of an inbred laboratory mouse strain, and mice fostered into families of a second, MHC-congenic mouse strain. Mature test mice were given a choice of two opposite-sex stimulus mice from the two MHC-congenic strains used for fostering, and were scored for several measures of preference. The results were non-significant in general, but females of two rearing groups spent significantly more time with mice of one MHC-type, and in most rearing groups, mice tended to spend more time with this same MHC-type. Other results showed that male test mice ejaculated indiscriminantly and that female wild mice mated to ejaculation more often in longer length trials, but showed no significant preferences. In this study, fostering seemed to have little or no effect on MHC-based mate preferences of wild house mice, and wild mice did not appear to be using the MHC to avoid inbreeding. However, some wild female mice used the MHC to choose potential mates.