Individual‐resource network between Xylocopa bees and plant resources: generalist species, specialist individuals?

Abstract

1. The resource partitioning hypothesis states that sympatric, morphologically, and functionally similar species can coexist by temporal separation or low food overlap. Also, the interindividual variations about the use of resources, i.e. individual specialisation, can promote the resilience and stability of their populations when an environmental disturbance affects food availability.2. Two sympatric and polylectic species of carpenter bees to test both the hypotheses of food niche partitioning and the occurrence of individual specialisation were used.3. The study was conducted in two Brazilian Savanna areas and the trophic niches of Xylocopa grisescens and X. frontalis were determined by the diversity of pollen types obtained from larval food samples. Individual‐resource networks were constructed to elucidate the patterns of resource use by the individuals of each species.4. The populations of the two bee species moderately overlapped their trophic niche. Xylocopa grisescens mainly used the pollen of non‐poricidal plants, whereas X. frontalis used pollen from plants with poricidal anthers. Individual‐resource networks of both species are weakly connected, highly specialised, and modular.5. In conclusion, the results suggest that the coexistence between Xylocopa grisescens and X. frontalis probably occurs due to food resource partitioning. Furthermore, the results about individual‐resource networks of both species seem to reveal the occurrence of interindividual variations regarding food resource foraging.