Prevalence and Mechanisms of Sex-Based Dietary Variation in East African Herbivores

Abstract

Intraspecific variation in niche space is increasingly recognized as important to species coexistence. Males and females face divergent ecological pressures, primarily stemming from sexual size dimorphism and differing reproductive strategies, that may produce intersexual niche differences. Using fecal metabarcoding data to reconstruct the diet of East African herbivores, I tested: 1. the prevalence of intersexual niche differences, 2. whether the magnitude of intersexual difference was correlated with sexual size dimorphism, 3. whether intersexual diet differences in bushbuck (Tragelaphus scriptus) led to intersexual differences in diet quality, and 4. whether intersexual diet differences in bushbuck were produced by variation in resource availability or variation in resource preference. I found intersexual dietary differences to be widespread, but the magnitude of the difference to be negatively correlated with grazing, not positively correlated with sexual size dimorphism. I found that diet quality did not differ between bushbuck sexes, but that larger males had higher quality diets than smaller males because of higher quality territories. These results point to underlying mechanisms that drive intraspecific variation, shaping individual and species-level resource utilization.