Ecology of Ring-Tailed Lemurs (Lemur catta) at the Tsimanampetsotsa National Park, Madagascar: Implications for Female Dominance and the Evolution of Lemur Traits

摘要

Lemurs are an ancient, extant primate radiation and have a number of traits (e.g. female dominance, low basal metabolic rate, weaning synchrony, cathemerality) which are unusual when compared to other primates, or even other mammals. The Energy Conservation Hypothesis (ECH) posits that the lemur traits are part of an adaptive complex selected to enable lemurs to conserve and extract energy from their seasonally and stochastically resource-poor environments. Data were collected on two groups of ring-tailed lemurs in the dry spiny forests of the Tsimanampetsotsa National Park, Madagascar, and tested aspects of the ECH through the following hypotheses: 1) ring-tailed lemur foods are seasonally and stochastically limited, 2) ring-tailed lemur nutrients and/or calories are seasonally and stochasically limited, 3) ring-tailed lemurs use behavioral mechanisms to save energy, and 4) the dry season is differentially stressful for female ring-tailed lemurs. Results from these data suggest that ring-tailed lemur plant foods, nutrients, and calories are seasonally and stochastically limited. Males appear to use behavioral strategies to conserve energy and females appear differentially stressed by the harsh conditions of the dry season. This study also documented extensive cathemeral activity in the ring-tailed lemurs, which may function to increase food intake, and limit thermoregulatory stress during hot days and cool nights. The aforementioned results are consistent with ECH, indicating that the lemur traits are an adaptive response to the environmental pressures of Madagascar. Furthermore, since dominance facilitates a feeding advantage for female lemurs, this trait likely allows for costly mammalian reproduction during times of predictable resource scarcity.