The potential for phenological mismatch between a perennial herb and its ground-nesting bee pollinator

Flowering time is shifting with climate change. Pollinators may respond differently to changes in temperature and moisture than the flowers they visit, resulting in a phenological  mismatch between species. Assessing the potential for such mismatches requires an understanding of the environmental factors that cue flowering and pollinator activity. Biological context is key to determining specific impacts of climate change, and therefore it is important to study mutualisms with pollinators of different nesting biologies.

A recent study by Olliff-Yang & Mesler published in AoBPfocused on the phenology of a perennial herb and its main pollinator, both native to the coastal dunes of north-western California: the silky beach pea (Lathyrus littoralis) and the ground-nesting solitary silver bee (Habropoda miserabilis). The authors measured current phenological overlap between the two species and took advantage of local fine-scale spatial variation in the timing of flowering and bee nesting activity to develop predictive models of flowering and flight period timing, based on variation in soil temperature and moisture. Temperature was the best predictor of both flowering and bee activity, although soil moisture also had significant influence. Bee nesting time was found to be more sensitive to changes in temperature than flowering, suggesting the two species life cycles may advance at different rates under a warming climate. Although the current phenological overlap between the two species is high, this differential response to temperature could result in a future mismatch. The results highlight that nesting biology may be critical in determining impacts of climate change on plant-pollinator relationships, as ground-nesting bees may respond differently than other bee species. In addition, this work reveals the value of studying bee species that nest in aggregations for understanding ground-nesting bee phenology.

Researcher Highlight

Rachael Olliff Yang obtained a B.S. in Environmental and Resource Sciences from the University of California Davis in 2012, and a M.S. degree in Biology in 2014. She is currently a PhD candidate in Integrative Biology at University of California Berkeley under the supervision of Dr. David Ackerly. She is also the membership chair for the California Botanical Society, where she works to promote the field of botany and support other early career botanists.

Rachael is a plant ecologist interested in the timing of plant life cycle events, and how shifts in events like flowering and fruiting with climate change will impact plant-animal interactions. She is currently investigating conservation strategies to mediate climate change impacts on plant-animal interactions.