Fig. 1. Effects of photoperiod transfer on body mass in Brandt's voles. During lactation, short photoperiod (SD) voles showed significantly lower body mass than long photoperiod (LD) voles. After weaning, the differences among the four groups occurred from 42 days of age to the termination of the experiment. Data are shown as means ± s.e.m. (N=8). ^*Significant difference between two groups (during lactation) or among four groups (during the postweaning photoperiod acclimation). LL, chronically long photoperiod; LS, preweaning long but postweaning short photoperiod; SL, preweaning short but postweaning long photoperiod; SS, chronically short photoperiod.