A missing link in mutualistic networks: symbiotic fungi in plant-animal interactions

Abstract We explored the hypothesis of an indirect mutualistic relationship (i.e., when the association between two species is modified by a third one) within a plant-animal seed dispersal network. Bats are important long-distance dispersers of many tropical plants, yet, by consuming fruits they may disperse not only the plant’s seeds, but also the endosymbiotic fungi within those fruits. We characterized fungal communities in fruits of Ficus colubrinae and in feces of Ectophylla alba to determine if passage through the digestive tract of the bats affected the total mycobiome. Results show a significant reduction, after passage through the gut, of fungi known to be plant pathogenic, while abundance of species known to have beneficial properties significantly increased. These findings suggest that the role of frugivores in plant-animal mutualistic networks may extend beyond seed dispersal: they also promote the dispersal of potentially beneficial microbial symbionts while hindering those that can cause plant disease.