Floral scent in bird- and beetle-pollinated Protea species (Proteaceae): Chemistry, emission rates and function

摘要: Evolutionary shifts between pollination systems are often accompanied by modifications of floral traits, including olfactory cues. We investigated the implications a shift from passerine bird to beetle in Protea for scent chemistry, and also explored functional significance pollinator attraction. Using headspace sampling gas chromatography–mass spectrometry, we found distinct differences emission rates chemical composition scents eight bird- four beetle-pollinated species. The amount emitted inflorescences species was, on average, about 10-fold greater than that bird-pollinated Floral consists mainly small amounts ‘‘green-leaf volatiles’’ benzenoid compounds, benzaldehyde, anisole benzyl alcohol. is dominated emissions linalool, wide variety other monoterpenes methyl benzoate, which imparts fruity odour human nose. number compounds recorded (45 versus 29 respectively). Choice experiments using Y-maze showed primary species, cetoniine Atrichelaphinis tigrina, strongly preferred simplex over those sympatric congener, roupelliae. This study shows insect-pollination can be associated with marked up-regulation compositional changes emissions.