Effects of Temperature and Photoperiod on Maximum Metabolic Rates in Plateau Pikas and Root Voles

Maximum metabolic rates (MMR) were determined in plateau pikas and root voles under different photoperiod and temperature acclimation (long day-warm temperature:16L∶8D,23℃;short day-warm temperature:8L∶16D,23℃;long day-cold temperature:16L∶8D,5℃;short day-cold temperature:8L∶16D,5℃).The result in dicated that 1)photoperiod had no effect on MMR of plateau pikas,but cold induced its increase (P<0.01),and temperature was the main physiological cue for seasonal variation in MMR;2)both of short photoperiod and cold could increased MMR in root voles (P<0.01),and they both became the physiological cue for MMR change in root voles.