Do abiotic conditions explain variation in the nutritional quality of wildflower pollens for bees?
Pollen is a critical food source for pollinators, including bees, and can impact how well these insects handle environmental change and disease. Previous research by Anthony Vaudo established that interspecies differences in pollen composition changed which pollinator species visited which plant species.
This study looked at intraspecies differences in pollen composition, comparing lipid and protein content within common, native, bee-visited wildflower species in a sagebrush steppe ecosystem. The team was studying if pollen exhibited biologically important intraspecies variations, and if those variations could be explained by climatic variables.
The team found that the two climatic variables seemingly linked with pollen variation were the climatic water deficits present during flowering, and the dewpoint in the autumn prior to pollen collection in the spring. Higher climatic water deficits were associated with a lower lipid and higher protein content. Similarly, a higher autumnal dewpoint was also associated with lower lipid content within species. Interestingly, higher climatic water deficits are a stressor for plants while higher autumnal dewpoints in the arid Western U.S. could indicate better conditions for plants, yet both were associated with lower lipid content.
The reason for this is not yet clear. While most variation seen in pollen composition in this study was significant but small, some of the variation (up to 30 percent for some species) is enough for bees to differentiate and may result in measurable performances differences. Because this study indicates that previous and current abiotic environmental factors may be associated with biologically important intraspecies differences in pollen content, more research is needed to determine the effects that weather variability and future factors may have on pollen and pollinators. This study adds to the growing body of research that views pollen composition as a variable and important factor to consider in conservation and restoration efforts.