Research

The adaptive function and ecological consequences of nectar secondary metabolites

 

Nectar is a reward for pollinators but can, surprisingly, contain noxious compounds called secondary metabolites. The characterization of these compounds in nectar and their impact on pollinators and pollination services is the focus of much of my research. What we know to date is that nectar secondary metabolites appear to be regulated independently from secondary metabolites in other plant parts, suggesting they may be adaptive. We also know that nectar secondary metabolites can deter bumble bees, though this response depends on the concentration of both the secondary metabolite itself and sugar in the nectar. In addition, the consumption of some nectar secondary metabolites can reduce bumble bee gut pathogen infections, although at least one compound, the alkaloid gelsemine, can also reduce bee ovary development. My ongoing work is looking at the role of nectar secondary metabolites in defending flowers from nectar robbers as well the abiotic and biotic factors, including nectar microbes, that influence nectar secondary metabolite concentrations.

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Multispecies interactions: impacts of herbivory on pollinators and pollination

 

Plants must simultaneously attract pollinators and defend themselves against herbivores; this can lead to tradeoffs between reducing damage and increasing pollination, which can impact plant fitness. I am currently addressing the ecological effects of herbivory on floral traits and pollination in natural populations of milkweeds (Asclepias spp.). In collaboration with independent research students, including students in the Research Experiences for Undergraduates (REU) program at Mountain Lake Biological Station, I have been looking at how timing and intensity of leaf damage alters plant reproductive traits, including flower morphology, nectar production and nectar chemistry, and the consequences for pollinator attraction and pollen movement. So far, we have generated more questions than answers, which means more opportunities for future undergraduate research!

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Pollinator communities in agroecosystems

 

Changes in land use, such as the conversion of native grasslands to pasture and croplands, has considerable effects on pollinator communities. In collaboration with Dr. Cameron Carlyle and a team of outstanding graduate students at the University of Alberta, I have been evaluating the diversity and abundance of native bees in canola fields and managed rangelands across the prairies of Alberta, Canada. This project, which sampled 68 sites over a 900-kilometer north-south transect, has revealed that while the type of land use does influence the number and type of bees found at a site, factors such as latitude, site ecology, and the distance to natural habitat can be more important drivers of native bee communities. We are still diving into this rich dataset and building on our findings through collaborations with landscape ecologists and systematists, so stay tuned.

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