Structure and roles in pollination networks between phyllostomid bats and flowers: a systematic review for the Americas

The Phyllostomidae family contains specialists and facultative nectarivorous bats that visit hundreds of plants. Understanding the topology of bat–flower networks is fundamental to understand ecosystem functions. However, this mutualism has rarely been studied on a community-wide level. We applied network theory to analyze the bat–flower interactions in the Americas. We addressed three questions: what is the state of knowledge of the diet of nectarivorous phyllostomid bats? Are bat–flower interaction networks random or structured? Are specialized nectarivorous bats more central than facultative bats? We compiled information on bat–flower interactions in the Americas and built four matrices (Americas, South, Central-North, and Antilles). We calculated complementary specialization, nestedness, and quantitative modularity; and we assessed the functional role of bat and plant genera using two centrality metrics. We found 61 phyllostomid bat species that visited 277 flowering plant species. The most important bats were Glossophaga soricina, Leptonycteris yerbabuenae and Anoura geoffroyi. The most important plant species were Ceiba pentandra, Cordia alliodora and Pseudobombax ellipticum. Most networks were specialized, modular, and non-nested; however, in the Antilles the networks were nested, unspecialized, and not modular. The specialist bat genera Glossophaga and Anoura were the genera most central as hubs, and the facultative genera Phyllostomus and Artibeus were connectors. The plant genera Ceiba, Pseudobombax, Ochroma and Pilosocereus were central as connector hubs. Nectarivorous specialist bats demonstrate more interactions, maintaining the entire system; meanwhile facultative bats were connectors, binding different parts of the network. There are big information gaps on diet for many specialist nectarivorous, and the importance of facultative nectarivorous bats is probably larger than what is believed.