Does body mass dimorphism increase male-female dietary niche separation? A comparative study of primates

Body mass plays an important role in shaping an individual's behavior, especially with respect to dietary behavior. Larger animals tend to consume higher quantities of low quality foods. In contrast, smaller individuals, with relatively higher metabolic rates require a high quality diet. Therefore, species that exhibit high amounts of sexual dimorphism in body mass should also display high levels of male-female dietary differentiation. This study investigated the relationship between body mass dimorphism and dietary sex differences for 38 primate species. We conducted multiple regressions using female body mass and body mass dimorphism as independent variables. We found that body mass dimorphism was significantly negatively correlated with male-female differences in fauna consumption using species values as well as phylogenetically independent contrasts. In addition, body mass dimorphism was positively related to male-female differences in percent time feeding using phylogenetically independent contrasts. Body mass dimorphism was not significantly related to male-female differences in the percent of fruit and leaves in the diet. The results suggest that, as body mass dimorphism increases, there is some degree of dietary niche separation between the sexes of primates. These results will be discussed in the context of existing studies of intersexual niche separation.