Extrafloral nectary plants in Brazilian biomes: Dominance of Cerrado and Fabaceae

Abstract

Extrafloral nectaries (EFNs) have been described in almost 4500 plant species, but there are several gaps in our knowledge of their occurrence and distribution. Here, we investigated the distribution and richness of EFN˗plants in Brazilian biomes. Data were extracted from published literature, and our analysis included only EFN˗plants that interacted with ants. A total of 234 EFN˗plant species in 47 families were registered in the Cerrado, Atlantic Forest, Caatinga, Pampa, and the Amazon. The Cerrado was evaluated in 65 % of all publications and had the highest richness (92 species) and the most exclusive species compared to the other biomes. Fabaceae was the most speciose family and was dominant in all biomes (except in the Amazon). Only 13 of 234 plant species were observed in more than one biome. In a network analysis, Qualea grandilflora, Turnera subulata and Plathymenia reticulata were relatively more important than other species, as they connected biomes and increased the community's cohesion. Our understanding of EFN˗plants is limited because the Fabaceae and Cerrado were overrepresented. In addition, the high exclusivity of flora within biomes adds a regional factor to our understanding of ant–plant interactions. Our data of plants visited by ants were compared with descriptive checklists of EFN˗plants, and 127 species and 16 families of EFN˗plants unknown from checklists were identified. Conversely, checklists contain hundreds of EFN˗plants from which interactions with ants are unknown, indicating a great potential for studies of ant–plant interactions and mutualisms.