Williams, C.F. Rick .
Effects of floral display size on the outcrossing rate of Delphinium barbeyi (Ranunculaceae).
Plants that produce many flowers are more attractive to pollinators, and pollinators may in turn visit more flowers on large plants. Such behavior may result in higher selfing rates via geitonogamy in plants with large versus small floral displays. I investigated the relationship between floral display size (flower and inflorescence number) and the outcrossing rate in a Colorado population of Delphinium barbeyi. Approximately 100 flowering plants were mapped within a 15x30m area and floral display size was recorded. The number of flowering stalks per plant ranged from 1-26, and total flower number ranged from 4-1400. Each flowering plant was genotyped for three polymorphic enzyme loci. Twenty seeds from each plant were genotyped to estimate outcrossing rates. The population level outcrossing rate (tm) averaged 72%. Small plants, with 3 or fewer stalks, tended to outcross at a higher rates (tm=0.79) than larger plants (>3 stalks, tm=0.66). There were weak negative relationships between individual plant outcrossing rate and inflorescence number (r= -0.201) and flower number (r= -0.199). In addition to floral display size, spatial proximity of neighboring plants and fine-scale genetic structure both influence the effective selfing rate in this population.
1 - Idaho State University, Department of Biological Sciences, Campus Box 8007, Pocatello, Idaho, 83209-8007, USA
floral display size
Presentation Type: Poster
Location: Special Event Center (Cliff Lodge)
Date: Tuesday, August 3rd, 2004
Time: 12:30 PM