Dominance and identity of the dominant bee drive bee diversity on flowers

Communities are characterized by the dominance of a few species, which are crucial for shaping communities. Bees compete for scarce resources, and offer an ideal system to study the effect of dominance on the diversity of bees. The effect of bee dominance is studied predominantly for the western honeybee, which can have negative effects in introduced sites. Solitary bees, stingless bees, native honeybees, and bumblebees can also be dominant on flowers. We test the hypothesis that dominance, regardless of the identity of the species, negatively influence diversity of bees on flowers. We analyzed 95,160 visits of 58 species of bees belonging to honeybees, solitary bees, and stingless bees on 59,211 flowers of 12 plant species across five years. Visitors were grouped into honeybees, solitary bees, and stingless bees. Proportion of the total abundance accounted by the most abundant species was considered as the estimate of dominance. Dominance negatively associated with richness and visitation rate of bees, but identity of bee functional group predicted the magnitude of the effects. Richness decreased with the dominance of honeybees and solitary bees, but not with the stingless bees. Visits of honeybees decreased when solitary bees dominated the visits. Visits of solitary bees decreased when honeybees or stingless bees dominated the flowers. We have shown that native bees of different functional groups can exert a similar negative effect on bee diversity in flowers like the invasive species do. Honeybees and stingless bees, though native in some parts, deteriorate bee diversity if augmented to ecosystems unnecessarily.