Meeting Abstract
Climate change is shifting phenology of diverse organisms and plant-pollinator mutualisms may be particularly sensitive to climate-driven phenological shifts. Flower characteristics, including when they bloom and whether they attract generalist or specialist pollinators, may determine the degree to which phenological changes affect plants and their target pollinators. In particular, potential differences in pollen limitation between these flower types will help determine fitness impacts of phenological mismatch. We measured pollen limitation of four forb species (Delphinium nutallianum, D. bicolor, Opuntia polyacantha, Allium textile) that are common in the sagebrush steppe ecosystems of Wyoming and that vary in bloom time (early vs. late) and flower type (attracting generalist vs. specialist pollinators). We hand-pollinated and bagged (to exclude pollinators) flowers of each species and left a control group of flowers of each species open to animal pollinators. We allowed flowers to senesce before collecting fruits and seeds of each flower. Flowers denied pollinators produced fewer, smaller seeds, suggesting little potential for autogamy in these species. Hand pollinated flowers produced more seeds of greater mass compared to open control flowers, suggesting strong pollen limitation in all four forb species. Open flowers on the earliest blooming flower, a generalist species, A. textile, produced fewer seeds than did open flowers on the early blooming specialist, D. nutallianum, potentially due to limited pollinators and low nutritional rewards of generalist flowers. Climate change may shift the phenology of plants and pollinators potentially limiting the size and number of seeds that native forbs produce, especially plants depending on specialized pollinators.
