Pollination ecology of Campanula species on Mt Olympos, Greece

Nine Campanula species occurring along the elevation gradient of Mt Olympos were studied regarding their pollination ecology. The main issues consider ed were 1) the relative importance of various insect taxa as Campanula poll inators, 2) the patterns of pollinators' size and activity as a function of altitude, 3) the effect of pollinator exclusion on floral longevity, and 4 ) the extent to which the morphological difference of C. versicolor from th e other Campanula species on Mt Olympos is expressed in its pollinating fau na. The vast majority of Campanula pollinators were solitary bees. Andrenid ae and Megachilidae bees (mainly Chelostoma campanulorum) dominated the pol linating fauna of most species. Melittidae and bumblebees were the commones t pollinators of high altitude species. Campanula versicolor differs from t he other Campanula species in that its corolla is not bell-shaped but Rat. Mainly Apis mellifera syrphid flies, and carpenter bees, unlike all other C ampanula species on Mt Olympos pollinated it. Ar the species level, rather large altitudinal differences of Campanula populations did not result into large diversification of their pollinating fauna. The insect visitation rat e to flowers decreased with altitude. When pollinators were excluded, the f loral longevity of the species examined increased three to five times. Neit her Rower phase (male of females) was consistently favoured in the absence of pollinators. The pollen loads of the different insect taxa (Apis mellife ra included) were of variable purity. The majority of Megachilidae bees car ried pollen loads of high purity. Pollen loads From insects visiting Campan ula species at high altitudes did not differ significantly in their purity from those visiting lowland species. The distribution of Campanula pollinat ors' body size along the altitudinal gradient exhibited a U-shaped pattern. No relationship was found between insect-pollinator body size and corolla size of Campanula species.