The evolution of floral design and display in animal-pollinated plants

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Flowers determine mating opportunities in animal-pollinated plants because pollinators transport male gametes (pollen) between flowers and plants. My research on floral evolution considers floral design, the characteristics of individual flowers, and floral display, the combined effects of all flowers displayed on a plant. First, I will investigate the evolution of floral display within the Polemoniaceae (Phlox family). Chloroplast sequence data will refine my earlier phylogeny of Polemonium. I will then compare changes in flower size, flower number, and inflorescence architecture among Polemonium species and within related genera with well-resolved phylogenies. Few studies have examined evolutionary changes in floral display among species, and none of these have considered plant size or growing season, two factors that affect the resources available for flowering. Second, I will assess how variation in pollinators (hawkmoth and hummingbirds) affects selection on floral design in Polemonium brandegei. I will expose artificial populations of plants to each pollinator separately, and examine relationships between floral traits and fitness, i.e., seed set and siring success. Siring success will be measured using genetic fingerprints estimated with AFLP's, amplified fragment length polymorphisms. Third, I will study how floral design, pollinator identity, and the surrounding community of rewarding flowers affect reproductive successs and hybridization between two species of lady's slipper orchid, Cypripedium. The mechanisms causing variation in hybridization rates are not well understood for most species, and have not been investigated in Cypripedium. In Cypripedium, dimensions of pollinator entry and exit routes in the trap-like flowers may determine which insects are effective pollinators, and the floral community likely affects which insects are present. These research objectives will contribute to my long term goals of understanding the evolution of floral display, and how variation in pollinators affects selection on floral design, and reproductive isolation between species.