Author Institution: Department of Biological Sciences, Kent State UniversityIndividual male deer mice (Perotnyscus maniculatus} respond to inhibitory (short) photoperiod with gonadal responses that range from azoospermia to normal spermatogenesis. We undertook the present study to determine if female deer mice exhibit similar variation in reproductive response to inhibitory daylength. Following 8 wk exposure to short days, reproductive tract weights of 25% of all individual females did not differ from those displayed by mice housed on stimulatory (long) photoperiod; reproductive tracts of all remaining short day mice weighed significantly less. Short photoperiod also significantly reduced body weight, albeit only in those mice with regressed reproductive tracts. These results demonstrate that female deer mice respond differentially to the inhibitory effects of short photoperiod. Taken together with previous results, the present findings indicate that populations of deer mice are composed of subsets of males and females that differ in reproductive response to short daylength
