Evaluating Critical Thermal Tolerances of Solitary Bees

Abstract

Climate change is predicted to impact pollinators through both direct and indirect mechanisms: by altering physiological stress through warming temperatures and by changing species interactions through the altered phenology and abundance of food sources and competitors. While research has been done to evaluate the indirect mechanism of climate change on bees, less is known about the direct mechanism of thermal stress. To fill this gap, we measured the critical maxima (CTmax) of 20 distinct solitary bee taxa to 1) evaluate differences in CTmax among taxa, 2) identify the life history-traits that influence thermal tolerance, 3) determine how well CTmax predicts success in hotter-than-average years, as a proxy for conditions under long-term warming, and 4) evaluate if there is local adaptation of CTmax at different elevations within the same species. We found significant differences among taxa in average CTmax, driven primarily by Lasioglossum inconditum, Halictus virgatellus, Sphecodes sp., and Habropoda sp. which had significantly lower CTmax and Pseudopanurgus bakeri, Halictus rubicundus, Osmia spp. and Megachile spp. which had significantly higher CTmax than all additional species tested. In evaluating the traits related to differences in thermal tolerance, we found that only mass significantly predicted CTmax, with larger bees demonstrating higher CTmax. We found that CTmax predicted responses to a hotter-than-average year, indicating a relationship between thermal tolerance and fecundity effects. Finally, we found evidence for local adaptation in CTmax to elevation only in Hylaeus spp. and Megachile spp. Taken together, these results indicate a direct mechanism of climate change impact beyond alterations in the phenology and abundance of interacting species and indicate a species-specific response to warming based on both the breadth of thermal tolerance and local adaptation of populations.

Local Knowledge Graph (13 entities)

Related Works

Items connected by shared entities, co-authorship, citations, or semantic similarity.

References (45)

5 in Knowledge Hub, 40 external