Pollen essential amino acids shape bat–flower interaction networks

Abstract Although pollen consumption by phytophagous bats has long been documented, the role of its protein and amino acid content in driving plant–pollinator interactions remains largely overlooked. Since animals can synthesise non‐essential amino acids (NEAA) but rely on dietary sources for essential amino acids (EAA), pollen may serve as a reward through an amino acid composition that is tailored to the nutritional demands of pollinators. This study examines how pollen protein and amino acid composition influence year‐round and seasonal bat–flower interaction networks in the Pantanal floodplain through extensive, long‐term, bat‐centred sampling. We predicted that EAA‐richer plant species would play central roles within the networks by exhibiting a higher normalised degree (i.e. how many bat species a given plant species interact with) and greater interaction strength (i.e. how intense the interactions are) in the network. The year‐round network consisted of eight plant species with chiropterophilous traits and 12 bat species from five feeding guilds. Protein content in the pollen of chiropterophilous plants ranged from 12% to 34%, with all essential and most non‐essential amino acids present. Bats from all guilds interacted more frequently with plants whose pollen was richer in EAA, but notably more so with insectivorous and carnivorous bats during the dry season. In contrast, nectarivorous, frugivorous and omnivorous bats maintained interactions year‐round with a full range of plant species. The year‐round bat–flower interaction network showed low specialisation ( H 2 ' = 0.29) and modularity ( M = 0.28), forming four distinct modules. In this network, the two plants with the highest richness of EAA formed separate modules and interacted with more bat species. Moreover, the richness of EAA in pollen strongly and positively affected the plant species' normalised degree and interaction strength. The great richness of EAA and pollen protein biomass, along with the effect of pollen EAA richness on bat–flower interactions, may suggest that the pollen of chiropterophilous flowers has evolved in response to the dietary requirements of phytophagous bats. Our findings underscore the essential role of pollen, not just nectar, as a key reward for attracting flower‐visiting bats, and therefore highlights pollen content as an important driver structuring pollination networks. Read the free Plain Language Summary for this article on the Journal blog.