Observations were consistent across space (18 sites in SW Iberian Peninsula) and time (three years) despite the presence of several closely related Cistus species whose flowers are morphologically similar. These findings are remarkable since bee specialization on harvesting pollen from a single flower species has been a questioned fact. Indeed, known cases have been explained by the absence of sympatric and synchronic flowers of the same plant genus or family, thereby, reflecting a lack of choices.
The study also uncovers that the bee’s flight phenology is synchronized with the blooming period of Cistus crispus, and that the densities of bee populations mirror the local densities of this flower. This case provides a nice example of the importance of interspecies interactions and dependencies for supporting and conserving biodiversity.