Can they take the heat? Assessing whether plant provenance enhances the suitability of flowering plants for pollinators under climate change

Heat waves can dramatically alter species interactions, and these extreme weather events are increasing in frequency, duration, and intensity. Conservation efforts need to account for extreme weather events in order to maintain long-term effectiveness. An increasingly popular conservation strategy is the establishment of habitat to support pollinator populations, many of which are in decline. Flowering plants can provide vital resources to pollinators, but currently, we lack evidence-based, climate-smart recommendations for where to source native plant seeds. We test whether plant genotypes from warmer regions provide higher quality floral resources to pollinators, and specifically, whether those resources are more resilient after exposure to heat waves. We focus on three perennial plant species that have broad geographic ranges across the eastern United States (Asclepias tuberosa, Monarda fistulosa, and Pycnanthemum tenuifolium). Wild-sourced plants of northern or southern genotypes were experimentally exposed to heat wave or control temperatures, and then deployed in a northern common garden field site. We assessed differences in plant performance, including blooming period, floral traits, rates of herbivory, seed set, and overall survival, as well as floral and non-floral insect visitation. Ultimately, the findings from this work can inform climate-smart recommendations for pollinator habitat seed sourcing in the face of climate change.