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Increased survivorship of testosterone-treated female house mice (Mus musculus) in high-density field conditions

Informally Refereed

Abstract

Differences in hormone levels influence sexual differences in aggression. survival, home-range size and dispcrsal in rodents. The role oftestosterone in establishing some of these differences in wild house mice was examined. Females treated with either 0·5 mg of testosterone enanthate (TE-treated) or oil (control), and an equal number of untreated males, were released onto three 'highway islands' and periodically recaptured over the following 7 weeks. Tbe islands are segments of highway cloverleafs enclosed by entrance and exit lanes that reduce emigration. Competition was encouraged by releasing large numbers of animals on the islands and by establishing fceding stations to enhance interaction opportunities. Significantly more TE-treated than control females were recaptured, because of differences in survival and not differences in capturability. Survival rates of TE-treated females exceeded those of control females early in the experiment but the reverse occurred near the end of the experiment. The two lypes of females did not differ in the number of captures at, or proximity of home ranges to, feeding stations. TE-treated females had smaller home ranges than control females, probably because the latter were frequently displaced by the former. Of the females recaptured at the end of the experiment. the TE-treated animals had fewer uterine scars, lighter uteri, heavier preputial glands and more tail scars than control females. TE-treated females resembled males by exhibiting increased intra-sexual aggression and having lower survival rates during the latter phase of the experiment. The benefits of, and hormonal basis for, aggressive behaviour appear similar in male and female house mice. Testosterone may mediate the competitive abilities of female house mice that have been shown in pr vious studies to be related to dominance and fitness.

Citation

Zielinski, W.J.; Vandenbergh, J.G. 1991. Increased survivorship of testosterone-treated female house mice (Mus musculus) in high-density field conditions. Animal Behavior 42: 955-967
https://www.fs.usda.gov/research/treesearch/34095