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Body size and abundance patterns of male orchid bees in a fragmented Neotropical landscape

Abstract:

Understanding the relationship between functional traits and fragmentation is crucial for promoting biodiversity and ecosystem function. Orchid bees (Euglossini) are important pollinators in Neotropical forests, but how body size may be associated with fragmentation and its influence on community organisation remains unexplored. We systematically sampled orchid bee communities across 15 plots in a fragmented area in the Ecuadorian Amazon basin to evaluate how patch size and isolation are associated with body size and abundance. Our samples comprised large-bodied bees (Eulaema, Euglossa and the parasitic Exaerete), with small Euglossa notably absent. The relative representation of Eulaema species of varying sizes changed across the fragmented landscape, leading to shifts in overall mean body size consistent with the prediction that larger-bodied pollinators are better at long-distance movement. Euglossa, the most abundant genus (67% of the total sample), was found across all patches regardless of body size. Euglossa intersecta and Euglossa orellana, the largest Euglossa in the region, were the most common species across the fragmented landscape. The abundance of male euglossines experienced a general decline with decreasing patch size and increasing isolation. However, at the species level, the abundance of some species was not affected at all. Because body size often mediates dispersal ability, thermoregulation, and resource use, we reinforce the importance of assessing body size patterns to understand changes in diversity, abundance and the composition of tropical pollinator communities in fragmented landscapes.