Sheila Schueller

The interactions between plants and their pollinators are among the most ornate and most intriguing phenomena of nature. Many of the world's flowering plants rely on animals for successful seed production, while many animals - insects and birds - rely on plant nectar and pollen for food. Islands present a particularly interesting pollinator-setting for plants which arrive from the mainland. The pollinators of islands are a smaller subset of the species present on the mainland, and they often include species which are unique to the island (endemics). What are the consequences of this difference in the number and nature of pollinators for the plants who depend on pollinators for reproduction? The answer depends on how "sensitive" a plant species is to pollinator changes, that is, how substitutable pollinators are from the perspective of the plant in terms of seed production and, subsequently, evolution of floral traits. Knowing how well plants reproduce on islands compared to plants of the same species growing on the mainland gives insight not only into the evolutionary role of pollinators have played in producing the diversity of flowers we see today (and in producing endemic island plant species), but also how plants will respond to current human-induced pollinator changes. The lowered diversity of pollinators in fragmented natural habitats is similar to the situation on islands.

My research on Santa Catalina Island deals with the effect of a change in hummingbird pollinators on a set of plant species which occur on the mainland and the Channel Islands. While the adjacent mainland has up to five species of hummingbirds, Santa Catalina Island has only two resident hummingbird species: Anna's and Allen's. Furthermore, the Allen's hummingbird on Santa Catalina Island is unique a subspecies of the migrating mainland species. By studying the same plant species across several island and mainland sites I can compare plant reproductive success across these different pollinator conditions. This will give a measure of plant "sensitivity" to pollinator conditions for each plant species studied. My research includes one introduced species- tree tobacco (Nicotiana glauca) - and one native species - California fuschia (Epilobium canum) because I want to address whether invasive species are less sensitive to "pollinator-challenging" environments (islands, fragments) than native species.