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ARS Home » Pacific West Area » Tucson, Arizona » Carl Hayden Bee Research Center » Research » Publications at this Location » Publication #217592
Title: Year-to-Year Variation in the Topology of a Plant-Pollinator Interaction Network

Author
item Alarcon Jr, Ruben
item WASER, NICKOLAS - UNIV. ARIZONA
item OLLERTON, JEFF - UNIV. NORTHHAMPTON

Submitted to: Oikos
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/11/2008
Publication Date: 7/11/2008
Citation: Alarcon Jr, R.N., Waser, N.M., Ollerton, J. 2008. Year-to-Year Variation in the Topology of a Plant-Pollinator Interaction Network. Oikos 117:1796-1807.

Interpretive Summary: Pollination of flowers by insects is a flagship interaction for studying mutualism and coevolution. However, until recently most research has focused on single plant species with one or a few pollinator species and with little consideration for between year differences in plant-pollinator interactions. Here we show that the pattern of species interactions varied through time in a montane meadow community from southern California. Furthermore, composition of the generalized species varied among summers, as did the identity of those species involved in specialized relationships. These differences are likely attributable to severe drought conditions experienced in the second summer of the 3 year study. This dynamic aspect of community-scale interactions has implications for both ecological and evolutionary inferences about pollination.

Technical Abstract: Pollination of flowers by insects is a flagship interaction for studying mutualism and coevolution. However, until recently most research has focused on single plant species with one or a few pollinator species. Vigorous discussion of the degree of specialization in pollination interactions, combined with advances in the analysis of complex networks, have now revitalized the study of entire plant-pollinator communities. Noticeably absent to date are attempts to quantify temporal variation in the structure and topology of plant-pollinator networks, and to determine whether the status of species as specialists or generalists is stable. Here we show that network topology varied through time in a montane meadow community from southern California, in that pollinator species did not form the same links with plant species across years. Furthermore, composition of the generalized core group of species in the network varied among summers, as did the identify of those species involved in the specialized relationships that comprise compartments within the network. These differences are likely attributable to severe drought conditions experienced in the second summer of the 3 year study. Interestingly, the pollinator community remained similarly highly nested in all three summers, even though species were packed into the nested matrix differently from year to year. These results suggest the plant-pollinator networks vary in detail through time, while retaining some basic topological properties. This dynamic aspect of community-scale interactions has implications for both ecological and evolutionary inferences about pollination mutualisms.