Palm pollination by bees, beetles and flies: Why pollinator taxonomy does not matter. The case of Hyospathe elegans (Arecaceae, Arecoidae, Areceae, Euterpeinae)

Abstract

The concept of adaptation-based pollination syndromes in which systematically bounded groups of pollinators service a particular host species has been applied to the palms. Except for beetle pollinated species, many palms lack major anthecological adaptations that apparently promote visits of a particular taxonomic group of insects. To address the question whether these palms have evolved insect-specific pollination systems, the interaction of the monoecious, protandrous palm Hyospathe elegans Mart. and visiting insects was studied in Amazonian Peru during an entire flowering period. At least 27 taxa of the orders Coleoptera, Hymenoptera and Diptera were recorded regularly visiting both types of flowers. To test whether flower visitation is taxonomically skewed, two sets of visitor samples from staminate and pistillate flowers were compared. There is no evidence to support the working hypothesis that there is a single optimal pollinator or a systematically bounded group of principal pollinators, based on the frequency of visits or the relative dominance within the visitor spectrum. Visitation rates suggest a mixed-species guild of nectar-feeding insects to be the commonest and most dependable pollinator group, along with an analogous guild of generalist-feeding copollinators. Hyospathe elegans and closely related species of Euterpe and Prestoea show common traits in their interaction with pollinators, such as phenological pattern, flowering behavior and allocation of rewards, and they also share a corresponding feeding guild. Given a preponderance of low taxonomic pollinator specificity in palm reproductive systems, pollination by a mixed-species guild may be widespread and the classification of 'mellitophilous' and 'myophilous' palms should be reconsidered.