Graduation Year


Date of Thesis Acceptance

Spring 5-5-2017

Major Department or Program



Susanne Altermann


Many plants exhibit within-species reproductive diversity, with populations self-fertilizing at varying rates throughout geographic space. This study explores the ecological drivers of the autogamy (within-flower self-fertilization) rate variation among populations of Campanula americana. Individuals from eight C. americana populations with a range of previously described autogamy levels were exposed to both high (sun) and low (shade) pollination environments. We found that population autogamy level was not associated with pollen limitation. We also found more pollen limitation in the shade than in the sun. Lower pollen limitation in the sun was likely due to more bumblebees which visit many more flowers/foraging bout. Dichogamy decreased with increased visitation and herkogamy decreased in populations with greater autogamy rates. However, neither dichogamy nor herkogamy were associated with pollen limitation.

Page Count


Subject Headings

Plants -- Adaption, Flowering of Plants, Self-pollination, Fertilization (Biology), Campanula -- American bellflower, Pollination -- Environment, Pollen -- Morphology, Flowers -- Anatomy, Pollinators, Whitman College -- Dissertation collection 2017 -- Biology Department

Permanent URL

Document Type

Public Accessible Thesis

Included in

Biology Commons



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