Abstract # 162:

Scheduled for Sunday, September 14, 2014 07:00 PM-09:00 PM: Session 22 (Decatur B) Poster Presentation


V. M. Schoof1, K. M. Jack2, T. E. Ziegler3, A. D. Melin4 and L. M. Fedigan5
1McGill University, Department of Anthopology, Montreal, Quebec, Canada, 2Tulane University, 3Wisconsin National Primate Research Center, University of Wisconsin-Madison, 4Washington University, 5University of Calgary
     Ecological variation strongly influences female reproductive endocrinology, frequently resulting in seasonal patterns linked to energetic constraints. Such energetic constraints may similarly affect males, but research has emphasized social factors, while largely ignoring ecological influences on male reproduction. We examine the effects of both ecological variation (food availability, rainfall season, temperature) and social factors (reproductive season, male age/rank) on fecal glucocorticoids (fGC, N=1342 from 24 males between July 2006-2010) and testosterone (fT, N=1056 from 19 males between July 2008-2010) in white-faced capuchins living in a seasonal environment. Repeated measures GLMMs indicate that male fGC was significantly predicted by fruit biomass (F=6.048, p=0.015), rainfall (F=9.381, p=0.002), male age/rank (F=26.698, p=0.002), and reproductive season (F=12.359, p<0.001), but not temperature (F=0.294, p=0.588). Analysis of residuals indicate that fGC levels were highest in the conception season, followed by the birth season, and were lowest in the gestation and post-birth period (Kruskal-Wallis: K=21.884, p<0.001). Male fT was significantly predicted by fruit biomass (F=10.528, p=0.001), male age/rank (F=38.562, p<0.001), and reproductive season (F=4.392, p=0.007), but not by rainfall (F=1.610, p=0.206) or temperature (F=0.953, p=0.330). However, analysis of the residuals indicates that when food availability was low, fT was high (Mann-Whitney U: Z=-2.211, p=0.027) and there was a similar trend for fGC (Z=-1.877, p=0.061). Our findings indicate that ecological conditions may play a more significant role in male reproductive patterns than previously considered.