Fruit Selectivity in Anthropoid Primates : Size Matters

Abstract

Certain features of both extant and fossil anthropoid primates have been interpreted as adaptations to ripe fruit foraging and feeding particularly spatulate incisors and trichromatic color vision. Here, we approach the question of anthropoid fruit foraging adaptations in light of the sensory and mechanical properties of anthropoid-consumed fruits in Kibale National Park, Uganda. We quantify the color, odor, size, and puncture resistance of fruits in Kibale that are consumed by anthropoid primates (N = 44) and compare these with the same traits of fruits that are not consumed by anthropoid primates (N = 24). Contrary to extant hypotheses, color and odor of anthropoid-consumed fruits do not differ from non-anthropoid–consumed fruits. However, we find that anthropoids in this system consume fruits that are significantly larger than non-anthropoid–consumed fruits, and with the exception of elephants that consume very large fruits, are the only dispersers of fruits with a surface area <4032 mm2, and a maximum diameter of 52 mm. While our findings do not support most extant hypotheses for the evolution of derived anthropoid primate traits as adaptations to ripe fruit foraging, we find some evidence to support the hypothesis that spatulate incisors may be an adaptation to foraging on large fruits, which tend to be harder.