The effect of flower color and nectar on Common Milkweed (Asclepias syriaca) pollination
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In this study we quantified the effect of floral pigmentation and nectar volume on pollinator visitation, behavior, and pollen movement in Asclepias syriaca (Common Milkweed). To do this we observed the frequency, type, and length of pollinator visits to plants at the Millport Conservancy in Lancaster, PA. After each visit we collected flower samples and quantified 1) the rates of pollen deposition and removal by pollinators, 2) nectar volume, and 3) pigment (anthocyanin) concentration. We found that 1) the number of pollinator visits were negatively correlated with pigmentation for non-honey bee (native) pollinators, 2) pollen deposition and removal increased with visitation, and 3) nectar volume decreased as pigmentation increased. Our results indicate that pollinators may prefer lighter colored A. syriaca flowers because they contain more nectar resources and that there may be a trade-off between flower color and nectar concentration. This project was made possible by funding from F&M's Hackman Summer Scholars Program.
Poster presented at the 2016 Autumn Research Fair at Franklin and Marshall College