The 82nd Annual Meeting of the American Association of Physical Anthropologists (2013)

Hungry, tired, and stressed: Why are lemur females dominant to males?


1Anthropology, University of Colorado Boulder, 2Anthropology, University of North Dakota, 3Institute for Population Genetics, University of Veterinary Medicine, Vienna

Saturday 3:45-4:00, 200ABC Add to calendar

Lemurs have a number of traits that are unusual when compared to other primates, such as female dominance. The Energy Conservation Hypothesis (ECH) posits that lemur traits enable lemurs to conserve and extract energy from their seasonally and stochastically resource-poor environments, and that this is particularly important for females who bear the energetic costs of gestation and lactation. Data were collected on two groups of ring-tailed lemurs in the spiny forests of the Tsimanampetsotsa National Park, Madagascar. We tested aspects of the ECH through the following hypotheses: 1) food nutrients and/or calories are seasonally limited, 2) behavioral mechanisms are used to save energy, and 3) the dry season is more stressful for females. We also investigated the nutritional contents of the lemurs' feces. Our results suggest that the protein to fiber ratio of foods consumed by all animals is higher in the wet season (t=3.18, df=84.5, p=0.001), that females consume more calories than males throughout the study (t=2.06, df=66.9, p=0.022), and both females and males consumed more calories in the wet season (t=2.09, df=85, p=0.021). Additionally, males appear to use behavioral strategies to conserve energy, and females appear differentially stressed. Interestingly, preliminary analyses suggest that some of the nutritional contents of the animals' feces vary between seasons and sexes, which could be an important direction for future research. This study supports the ECH and suggests that lemur female dominance facilitates a caloric advantage, which is likely critical to their ability to survive and reproduce during resource-poor periods.

Grant Sponsors: National Science and Engineering Research Council of Canada, 296264; National Science Foundation, 1028708; and National Geographic Society, 8880-11.

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