Grey Mouse Lemurs’ response to acute caloric restriction before reproduction supports the “Thrifty Female Hypothesis”

Summary The thrifty female hypothesis states that females would preserve more of their energy reserves during winter than males, because of a sex specific time-frame of energy allocation to reproduction. As males reactivate their reproductive axis before the mating period, while females mainly allocate energy in gestation and lactation, we make the hypothesis that males would have to use shorter torpor bouts and longer periods of normothermic activity in order to promote spermatogenesis during winter, a period of low food availability. Here we applied an acute two-week 80%CR in males and females grey mouse lemurs, shortly before the mating period. We show evidence of thriftier phenotypes in wintering females, which performed deeper and longer torpor bouts than males, and ultimately lost less body mass. Our results thus support the thrifty female hypothesis in a seasonally breeding primate, and reinforce the concept of a sex-biased trade-off in using torpor, which might ultimately benefit to reproduction and survival.