Ecological and Reproductive Correlates of Energy Balance in Wild Moor Macaques (Macaca maura) Using C-Peptide Measurements

ECOLOGICAL AND REPRODUCTIVE CORRELATES OF ENERGY BALANCE IN WILD MOOR MACAQUES (MACACA MAURA) USING C-PEPTIDE MEASUREMENTS Lavinia Germani a, Cédric Girard-Buttoz b, Michael Heistermann c, Putu Oka Ngakan d, Monica Carosi a aDepartment of Sciences, Roma Tre University, Rome, Italy; bDepartment of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; cEndocrinology Laboratory, German Primate Centre, Leibniz Institute for Primate Research, Göttingen, Germany, dFaculty of Forestry, Hasanuddin University, Makassar, Indonesia Energy is a key factor for wild animal survival. Reproduction and energy balance might be affected by seasonal variation in food availability and reproductive costs in both sexes. This is relatively well established for seasonally breeding primates living in highly predictable environments and showing intense male competition, yet little is known about factors affecting energy balance in species with weaker ecological and reproductive seasonality. Here, we investigated the ecological and reproductive correlates of energy balance in adult individuals of the moderately seasonal, polygynandrous and tolerant moor macaques, Macaca maura. We studied one social group living in the karst forests of south Sulawesi (Indonesia), which provide relatively stable food supply. Urine samples (n=120; 11 males, 13 females) were collected for 11 months across 2 field seasons (each covering both dry and wet season) and analysed for urinary C-peptide (UCP), a biomarker of energy balance. We tested the effect of fruit availability on the energy balance of males and females of different reproductive states (each likely related to different energetic costs). We also tested male UCP in response to the presence of potentially fertile females. Both male and female UCP levels positively responded to fruit availability increase, and the strength of this relationship was similar in males and in cycling and lactating females. Pregnant females, however, responded more strongly than other groups, suggesting that they are more sensitive to ecological variation. Finally, the presence of potentially fertile females did not influence male UCP levels. Although based on a small sample size, these results challenge the applicability of classical socio-ecological theories to tolerant primates inhabiting a relatively steady environment since, in these species, competition for access to food resources might be as important in males as in females and male energetic investment in mating competition might be relatively low.