Ha, Melissa K. , Ivey, Christopher T. .
Pollinator-mediated interactions between Clarkia unguiculata and its neighbors are context-dependent.
The context-dependent nature of biotic interactions shapes their net impact evolution and community structure. Indirect biotic interactions can vary with the abundances of mediating species or other community members. For example, interactions between co-flowering plants that are mediated by shared pollinators may range from competition to facilitation depending on the floral neighborhood or pollinator community. We conducted a factorial field experiment using arrays of focal Clarkia unguiculata, in which flowering time and floral neighborhood were manipulated. Early- and late-flowering focal plants were placed in arrays with either no neighboring plants, C. biloba neighbors, non-congener neighbors, or additional C. unguiculata plants as a density control. We compared pollinator visitation, pollen deposition, and pollen limitation of per-capsule seed set among treatments. Pollinator-mediated interactions varied with season and floral neighborhood. Clarkia unguiculata was facilitated only by C. biloba and only during the early season whereas competition occurred only between non-congener neighbors during the late season. Pollinator visitation did not explain variation in pollen limitation, but pollinator effectiveness may influence pollen limitation in this system. Our results suggest that indirect biotic interactions can be context-dependent. Pollination, reproduction, and establishment in a community may vary temporally with changes in plant and pollinator communities. Evaluating the net result of pollinator sharing over time informs our understanding of its ecological consequences.
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1 - University of Massachusetts Amherst, Graduate Program in Organismic and Evolutionary Biology, 219 Morrill Science Center, 611 North Pleasant St., Amherst, MA, 01003, USA
2 - California State University, Chico, Department of Biological Sciences, California State University , Chico, CA, 95929, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Melrose/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 2:30 PM
Candidate for Awards:None