Diversity, flower visitation frequency and generalism of pollinators in temperate rain forests of Chiloe Island, Chile

Abstract

Species richness and taxonomic composition of pollinator assemblages are documented for 26 plant species from temperate rain forests of northern Chiloe Island, southern Chile (42 degrees 30'S). We investigated the patterns of generalism and specialization among plants and animal pollinators by comparing the flower visit frequency by different pollen vectors during the spring and summer months of three consecutive years (2000-2002). Species studied exhibited a range of floral morphologies (radial vs. zygomorphic, open vs. tubular) and rewards (nectar and/or pollen). Overall, we recorded 172 pollinator species, with an average of 6.6 species of pollen vectors/plant species. Pollinators visited an average of 15.2 plant species/pollen vector. Pollinator assemblages were dominated by Coleoptera (75 species), Diptera (56 species) and Hymenoptera (30 species), but passerine birds and hummingbirds were also important. The most specialized plants were vines, including the bee-pollinated genus Luzuriaga (Philesiaceae) and two endemic species of hummingbird-pollinated Gesneriaceae. Hymenoptera contributed 41.2% of all visits, with the bumblebee Bombus dalhbomi accounting for 22.5% of these. Plants with unspecialized flower morphology supported a higher species richness of pollinators, but visiting rates did not differ from specialized flowers. 2005 The Linnean Society of London, Botanical Journal of the Linnean Society.