Differential responses to same and opposite sex odors by adult house mice are associated with anogenital distance

Intrauterine position (IUP) of female and male fetuses in litter-bearing ma mmals can affect their physiology, morphology and behavior. The relationshi p between anogenital distance (AGD) and IUP was used as a bioassay for the degree of exposure of female and male fetuses to hormones in utero. Based o n laboratory work in several rodent species, the following predictions were made for house mice (Mus musculus domesticus): (1) female mice should pref er odors from males with larger AGDs because such males are more aggressive , could protect more resources, and are better parents: than males with sma ller AGDs; (2) male mice should prefer odors from females with smaller AGDs because these females produce more offspring and are better parents than f emales with larger AGDs. We also tested the prediction that within sexes, m ice should avoid odors from mice with larger AGDs because such mice are mor e aggressive. Responses to odors in traps were used to test these predictio ns for house mice living in outdoor enclosures using odor-baited traps. Bot h predictions were confirmed. Furthermore, mice of both sexes tended to avo id odor cues from individuals of the same sex that had larger AGDs, probabl y to decrease chances of an aggressive encounter that could result in injur y.