The development of sex differences in ring-tailed lemur feeding ecology

Abstract

Sex differences in feeding ecology may develop in response to fluctuations in physiological costs to females over their reproductive cycles, or to sexual size dimorphism, or function to minimize feeding competition within a group via resource partitioning. For most mammal species, it is un- known how these factors contribute to sex differences in feeding,orhow thedevelopmentofmalesandfemalesreflects these intraspecific feeding differences. We show changes in dietary composition, diversity, overlap, and foraging behavior throughout development in ring-tailed lemurs (Lemur catta) and test how the development of sex differences in feeding is related to female costs of reproduction and year-round re- source partitioning. Sex differences in dietary composition were only present when females were lactating, but sex dif- ferences in other aspects of feeding, including dietary diver- sity,andrelativetimespentfeedingandforaging,developedat or near the time of weaning. Sex difference in juveniles and subadults, when present, were similar to the differences found in adults. The low year-round dietary overlap and early dif- ferences in dietary diversity indicate that some resource partitioning may begin with young individuals and fluctuate throughout development. The major differences between males and females in dietary composition suggest that these larger changes in diet are closely tied to female reproductive state when females must shift their diet to meet energetic and nutritional requirements.