| In plant communities, flowers are patchy in space and time over many scales. Flower-feeding animals make complex foraging decisions in this setting, but they may respond in characteristic ways to variation in floral distribution and the presence of different plant species. For plant species that rely on animals to disperse their pollen for sexual reproduction, pollination will reflect these animal foraging decisions. Because many pollinators are highly mobile and return to foraging areas over time, they may affect plant pollination over scales broader than typically considered (a few metres and within foraging bouts). My dissertation explores how individual pollinators respond to floral resource variation, and the implications for plant pollination success. I do so over relatively broad spatial and temporal scales, by studying the interactions between bumble bees (Bombus spp.) and three plant species (Delphinium barbeyi, Gentianopsis detonsa, and Gentiana parryi) in Rocky Mountain subalpine meadows. As an assemblage, bumble bees concentrated their visits in resource rich areas over tens to hundreds of metres. This caused one plant species to act as a bumble bee magnet in an area, which increased the pollination of another plant up to 30 m away. In addition, many individual bees returned repeatedly to small areas, which also caused positive pollination interactions between plants. When a preferred flower declined, bees stayed faithful to their site and not their preferred species. Consequently, a newly-blooming plant quickly inherited a set of returning bees. I also showed that as a result of its late-flowering time, Gentiana receives visits by both female and male bumble bees. Intriguingly, the males were abundant and effective pollinators, despite not being considered by researchers as such. Overall, my work shows that pollinators can respond to flowers over broad spatial and temporal scales that can affect plant pollination success in unrecognized ways. |
