Gender markedly modulates behavioral thermoregulation in a non-human primate species, the mouse lemur (Microcebus...

Age and gender are known to significantly modulate thermoregulatory capacities in mammals, suggesting strong impacts on behavioral adjustments, which are used to minimize the energy costs of thermoregulation. We tested the effects of sex and age on spontaneous choice of ambient temperature (Ta) in a non-human primate species, the mouse lemur (Microcebus murinus). The animals acclimated to both winter and summer photoperiods, two seasons significantly modifying thermoregulation function, were experimented in a thermal gradient device. During winter, adult males did not show preference for warm Tas whereas old males did. In contrast, female mouse lemurs of both age categories exhibited great preferences for warm Tas. Acclimation to summer revealed that males selected colder Ta for the day than during the night. Such behavior did not exist in females. Old females explored and selected warmer nests than adult ones. This study raised novel issues on the effect of gender on thermoregulatory capacities in the mouse lemur. Females probably use behavioral adjustments to limit energy expenditure and might prefer to preserve energy for maternal investment by anticipation of and during the breeding season. Further experiments focusing on female thermoregulatory capacities are needed to better understand the energy challenge that may occur during winter and summer in female mouse lemurs, and whether this trade-off changes during aging.