Under the petals: the genetics and developmental evolution of the nectar reward in Penstemon

Plants may attract specific pollinators to efficiently move pollen between flowers facilitating reproductive success. To attract and use specific pollinators, flowering plants have evolved a diversity of colors, color patterns, metabolic rewards, and shapes. The flower nectar reward is a key trait used to attract pollinators and keep them returning. I use the genus Penstemon, which has 10-20 independent transitions from bee pollination to hummingbird pollination to investigate the convergence and development of nectar reward traits. In my first chapter, I explore the nectar producing organ, the nectary, by characterizing the nectary area and testing its relationship to pollinator type using 19 species of Penstemon. In chapter two, I annotate the Penstemon barbatus genome to provide genomic resources for further Penstemon research. In my third chapter, I use transcriptomics to investigate Penstemon nectary development in early-stage flower buds, the production of nectar in open flowers, and the replenishment of nectar pre- and post-nectar removal. In my fourth chapter, I compare two Penstemon species adapted to contrasting bee and hummingbird pollinators to understand if key differences between species have gene expression differences underlying previously identified regions of the genome where genetic variation explains variation in nectar volume.