Using a Phylogenetic Framework to Assess the Role of Fruit Size in Food Selection by the Andean Night Monkey (Aotus lemurinus)

Abstract

The study of diet and food selection is foundational to understanding how primates interact with their environment. Due to the potential evolutionary relationship between fruit physical traits and frugivory in animals, our goal was to understand the composition and the evolutionary relationships of plant species in the Andean night monkey’s diet (Aotus lemurinus) in Pijao-Quindío, Colombia. We hypothesize that phylogenetically related plants share fruit physical traits, such as size, which make them more likely to be selected. We estimated the diet of two groups of monkeys through feeding time (4,431 min) and surveyed fruit-bearing trees available (from 40 spp.) through five phenological transects from July 2018 to July 2019. To evaluate whether feeding time is influenced by fruit size, controlling for phylogeny, we mapped the fruit size of each species onto the phylogeny and tested for the phylogenetic signal using comparative phylogenetic methods. We found that the Andean night monkey selected some fruit species (of 29 spp. selected) disproportionately more often relative to their abundance and spent more time feeding on fruit-bearing trees belonging to the Rosidae subclass than other subclasses (pattern also found in other populations in Colombia). Although fruit size had a strong phylogenetic signal, it was not significantly related to time spent feeding on fruits, even after controlling for the phylogenetic relationships among fruit species. Our results suggest that fruit size does not influence fruit selection and that we need to assess other fruit traits (physical and phytochemical) to better understand the coevolutionary dynamics in this tropical forest.