Piacentini & Varassin 2007 (Article) Bromeliaceae

Interaction network and the relationships between bromeliads and hummingbirds in an area of secondary Atlantic rain forest in southern Brazil

Author(s):—V.Q. Piacentini & I.G. Varassin

Publication:—Journal of Tropical Ecology 23 : 663–671. (2007)

Abstract:—The reciprocal importance of bromeliads and hummingbirds has been proposed for many years, evensuggesting coevolution between these two groups. Nevertheless, data are lacking that allow a better test of the relationships involved. Here we investigate the relationship between bromeliads and hummingbirds in an area of secondaryAtlanticrainforestin southernBrazil.Thestudyexaminedtheinteractionsamong12species ofbromeliadand 10 of hummingbird at Reserva Natural Salto Morato, Paran´a state. The number of flowering species of bromeliadand the species richness and abundance of hummingbirds were quantified monthly between November 2004 andOctober 2005. Focal observations on each bromeliad species were made to determine the hummingbird visitors.Neither species richness nor abundance of hummingbirds were related to bromeliad phenology. Together with themonthly variation in visit frequency by a given pollinator to a given plant, these factors indicate a generalizationin the use of bromeliads by hummingbirds and argue against tight coevolution.
Ramphodon naevius and Thaluraniaglaucopis were the main pollinators in the community. Aechmea nudicaulis was the most generalist bromeliad species.The generalist species interacted with other generalists or with asymmetric specialists and there was no specialist– specialist interaction. This produced a strongly organized and nested matrix of interactions. This nestedness is similartootherplant-pollinatorsnetworks, supporting the hypothesis that thee volutionary relationship between bromeliads and hummingbirds is no stronger than that of other pollination networks.

Keywords:—Bromeliaceae, coevolution, hummingbirds, interactions, nestedness, phenology, pollination systems