Female house mice recognize infected males, but do not avoid mating with them (#706)
Previous studies found that female house mice (Mus musculus) are more attracted to the scent of healthy males than infected ones, even with avirulent pathogens and parasite. Such odour preferences may function to reduce risks of disease transmission or to obtain healthy, disease-resistant mates. However, it is still unclear whether such odour preferences result in differential male reproductive success (sexual selection). Therefore, we performed mate-choice experiments with wild-derived mice. We allowed female mice to freely choose to mate with a healthy male, a Salmonella enterica-infected male, or both, and we used genetic paternity analyses to compare the males' reproductive success. Before the experiments, we first confirmed that the infection did not impair the males' mating behavior (attempts to mount females). We conducted the experiment in a laboratory setting (three large connected cages) and we repeated the experiment in large, indoor semi-natural enclosures. In the enclosures, we found that 86% of females were initially more attracted to the control males (initial social preference); however, there was no difference in male reproductive success in either setting. Females often mated with both males (laboratory setting 32%, enclosures 44%), which shows that females frequently mate multiply when they can choose their mates, even despite differences in male infection status. Thus, females could recognize the infected males, and yet they showed no mate choice and often mated with them. Our findings raise caveats about mate choice studies that rely on proxy measures, such as odor preferences or time spent with potential mates.