Do sex differences affect behavioral thermoregulatory strategies in lemur species?

Abstract

Thermoregulation is the ability for an animal to maintain its internal body temperature. Due to the high costs of regulating temperature physiologically, behavioral thermoregulation is more energy efficient. While previous studies have characterized thermoregulatory behaviors in mammals, few have examined how sex differences influence thermoregulatory behaviors. Sex differences in energy costs can be attributed to the contrast in male and female parental investment. Females endure more energetic costs while pregnant as well as costs of lactation. Males on the other hand acquire smaller energetic costs for sperm production and male-male competition during the breeding season. Lemurs make for interesting models to test for sex differences in behavioral thermoregulation as they have relatively low metabolic rates and clear sex differences in parental investment. Here we test the hypothesis that females will exhibit greater use of thermoregulatory behaviors than males using 21 individuals from 3 species of lemurs (Lemur catta, Eulemur flavifrons, Eulemur mongoz) housed at the Duke Lemur Center. Data collection involved scan samples recording behavior, sun or shade exposure, substrate, individual identification, ambient temperature, wind and humidity. Data analysis indicates no clear sex difference in behavioral thermoregulation. Males and females both showed use of thermoregulatory behaviors through decreasing energy conserving behaviors as temperature increased. In some instances, females also displayed patterns opposite of what was expected. Data was further distinguished between breeders and non-breeders but no clear patterns were found. Overall, these results suggest no clear sex difference of behavioral thermoregulation.