Elle, Elizabeth .
Selection by climate and pollinators on mating-system-associated traits.
Floral traits can predict the mating system, with small-flowered forms normally having higher selfing rates than large-flowered forms. High selfing rates are often assumed to result from reduced attractiveness to pollinators coupled with passive autogamy due to the close proximity of sexual parts in small flowers. In contrast, outcrossers are assumed to be highly attractive to pollinators, which select for larger, more rewarding floral displays. Selection by pollinators may not be the only mode of selection on floral traits that affect the mating system, however. Small flowers may evolve due to selection for rapid development in ephemeral environments, where reproducing quickly is advantageous because it ensures some fitness. Rapidly developing plants may be of small stature with small flowers, simply because smaller body sizes can be built more quickly. In a selection experiment on Collinsia parviflora, I demonstrate that selection for earlier flowering results in plants with smaller flower sizes and higher autonomous selfing ability. Selection gradients measured in the field show selection for earlier flowering in dry sites (where the local populations are small-flowered), but in wet sites (where local populations are large-flowered) there is selection for larger flowers, likely due to pollinator choice. These results suggest that both biotic and abiotic selection should be considered in the study of mating system evolution.
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1 - Simon Fraser University, Department of Biological Sciences, 8888 University Drive, Burnaby, British Columbia, V5A 1S6, Canada
evolution of selfing
plant growth and development
Presentation Type: Oral Paper:Papers for Sections
Location: Council Chambers/SUB
Date: Monday, July 28th, 2008
Time: 3:00 PM