  The balance between energy intake and expenditure is essential and crucial
for survival for all organisms. The energy management is closely linked to the
ecology. Thus, changes in environmental conditions can be challenging,
especially for the animals physiology. Different strategies of thermoregulation
have evolved and heterothermy seems to be the most efficient way for saving
energy. Daily torpor, a temporally controlled reduction of the metabolic rate
and body temperature, is one form of heterothermy and recent studies revealed
that this physiological strategy is used by many tropical and subtropical
species. Yet, little is known about torpor in bats and their intraspecific
thermoregulatory flexibility. Therefore, three populations of the Malagasy bat
species Triaenops menamena were investigated, to examine their metabolic rate,
skin temperature and related energy expenditure during normothermic and torpid
states in context of different microclimatic conditions. This study exposed
significant physiological differences among these three populations along a
gradient of fluctuation in environmental conditions. The greater the
fluctuations in ambient temperature and humidity, the higher was the general
resting metabolic rate and the rate of its reduction, but the lower was the
torpid metabolic rate. This species shows a highly adaptive flexibility in
their physiology and are able to cope with unfavorable environmental conditions
by using different strategies of thermoregulation and hypometabolism, which is
beneficial regarding ongoing climatic changes.
