Stone, Judy , Jenkins, E. G. .
Pollinator Abundance and Pollen Limitation of a Solanaceous Shrub on an Elevational Gradient in Costa Rica.
Populations at geographic range limits may frequently encounter changing biotic interactions as well as abiotic constraints. A conundrum in plant population biology, the frequent apparent overproduction of flowers, is thought to be a response by plant populations to unpredictable pollinator environments, such as those that may be expected at the species range. We studied pollinator visitation rates and pollen limitation of fruit set in populations of Witheringia solanacea, a widespread bee-pollinated species. We compared two populations in the south and two in the north of Costa Rica, with each region encompassing a lower montane site at the limit of the species range with small plant populations, and a premontane site where population densities were high. Populations in the south, where the climate was favorable, had higher pollinator visitation and higher natural fruit set, and showed only minor pollen limitation as compared with northern populations at windy sites near the continental divide. Lower montane populations had lower pollinator visitation rates than premontane populations but did not show more pollen limitation of fruit set. In general, pollen limitation was not inversely proportional to pollinator abundance but was higher where the climate is unpredictable.
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1 - Colby College, Department of Biology, Waterville, Maine, 04901-8857, USA
2 - Colby College, Department of Biology, Waterville, Maine, 04901, USA
Presentation Type: Oral Paper:Papers for Topics
Location: Lake Ontario/Hilton
Date: Tuesday, July 10th, 2007
Time: 11:30 AM