Evidence for beetle pollination in the African grassland sugarbushes (Protea: Proteaceae)

摘要: Most lineages in the African genus Protea consist of species with large unscented flowers pollinated principally by birds, and several these also show evidence shifts to rodent pollination, associated concealed yeasty-scented flowerheads. In this study we investigated hypothesis that brightly coloured fruity-scented flowerheads four (P. caffra, P. simplex, dracomontana welwitschii) represent a novel shift from bird insect pollination grassland lineage genus. These are visited wide range insects, but cetoniine beetles were found be most important pollinators because their abundance, size relatively pure pollen loads. Three putatively insect-pollinated have presented at ground level, experiments showed preferred inflorescences level those artificially elevated height shrubs small trees. Relative birds infrequent visitors all species. The nectar contained xylose, as documented previously bird- rodent-pollinated species, suggesting is phylogenetically conserved trait. However, very low concentration (ca. 8%), short nectar-stigma distance fruity scent florets appear traits specialisation for beetles.