Symbioses: Plant, Animal, and Microbe Interactions
Elliott, Susan , Irwin, Rebecca .
The role of pre-dispersal seed predators in mediating pollination benefits for Delphinium barbeyi (Ranunculaceae).
PLANTS are visited by a diversity of mutualist and antagonist animal consumers, which can singly and synergistically influence plant reproduction. Factorial experiments have demonstrated that the benefit plants receive from pollination may depend on the intensity of herbivory or seed predation occurring before, during, or after pollination in some, albeit not all, cases. To understand the ecological and evolutionary consequences of multispecies interactions, we need to determine if these additive or non-additive patterns occur over natural frequencies of consumer interactions, what mechanisms could be driving these patterns, and the degree to which these patterns occur at the individual- and/or population-levels. In this study, we demonstrate the degree to which the benefit of pollination is dampened by pre-dispersal fly seed predation in Delphinium barbeyi (Ranunculaceae). We then mechanistically assess whether these patterns could be driven by preferential seed predator attack rates and/or increased damage per attack on plants with more pollen and seeds. Finally, we hierarchically partition the variance in these outcomes due to plant-, and patch-level characteristics and we experimentally test the effects of plant density on pollinator visitation, pollen receipt, seed predation, and seed production. Results suggest that the non-additive effects of pollination and pre-dispersal seed predation on plant reproduction may be driven more by increased damage per attacked fruit than by preferential oviposition on plants with more pollen and seeds in some sites. In addition, pollinators distribute themselves evenly over patches of plants such that pollination and seed production are independent of plant density. Overall, this study demonstrates how a detailed mechanistic approach can enhance our understanding of when and why we may expect to see additive or non-additive outcomes of multispecies interactions.
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1 - Dartmouth College, Department of Biological Sciences, Gilman Lab, Hanover, New Hampshire, 03755, USA
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 31st, 2006
Time: 10:30 AM