GEOGRAPHICAL VARIATION OF THERMOREGULATION IN WILD POPULATIONS OF MUS-MUSCULUS AND MUS-SPRETUS

Thermoregulation was studied in the house mice Mus musculus (Linnaeus, 1758) from Warsaw region (Dziekanow Lesny) and from Sofia (Kostinbrod) and in Mus spretus (Lataste, 1883) from southern France (Montpellier). The thermoregulation curves obtained in these three groups of mice were significantly different. The lowest values of metabolism rates in thermoneutral zone, assumed to approximate BMR values fell in range from 30-degrees to 33-degrees-C. The body temperature in mice subjected to 5-degrees-C to 30-degrees-C range of temperatures remained fairly similar. The lowest intensity of thermoregulation, expressed in % per degrees-C, was observed in Mus spretus while the lowest insulation index was found in Mus musculus from Dziekanow. The results indicate certain adaptations in metabolism rate of the rodent species studied, relevant to the conditions in the habitats where rodents live.