Invasive mutualisms and the structure of plant?pollinator interactions in the temperate forest of north-west Patagonia, Argentina

MORALES, C.L. Y M.A. AIZEN

JOURNAL OF ECOLOGY (PRINT)

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2006 vol. 94 p. 171 - 180

0022-0477

1Alien species may form plant?animal mutualistic complexes that contribute to theirinvasive potential. Using multivariate techniques, we examined the structure of aplant?pollinator web comprising both alien and native plants and flower visitors in thetemperate forests of north-west Patagonia, Argentina. Our main objective was to assesswhether plant species origin (alien or native) influences the composition of flower visitorassemblages. We also examined the influence of other potential confounding intrinsicfactors such as flower symmetry and colour, and extrinsic factors such as flowering time,site and habitat disturbance.2Flowers of alien and native plant species were visited by a similar number of speciesand proportion of insects from different orders, but the composition of the assemblagesof flower-visiting species differed between alien and native plants.3The influence of plant species origin on the composition of flower visitor assemblagespersisted after accounting for other significant factors such as flowering time, bearingred corollas, and habitat disturbance. This influence was at least in part determined bythe fact that alien flower visitors were more closely associated with alien plants thanwith native plants. The main native flower visitors were, on average, equally associatedwith native and alien plant species.4In spite of representing a minor fraction of total species richness (3.6% of all species),alien flower visitors accounted for>20% of all individuals recorded on flowers. Thus,their high abundance could have a significant impact in terms of pollination.5The mutualistic web of alien plants and flower-visiting insects is well integrated intothe overall community-wide pollination web. However, in addition to their use of the nativebiota, invasive plants and flower visitors may benefit from differential interactions withtheir alien partners. The existence of these invader complexes could contribute to thespread of aliens into novel environments.