Tuesday, August 8, 2017: 4:20 PM
E141, Oregon Convention Center
Background/Question/Methods
Extreme weather events, such as heat waves, are natural features of all ecosystems, but our understanding of how these brief but intense events scale up to influence population dynamics and species interactions is poor. As anthropogenic climate change continues to make heat waves more frequent and more intense, it becomes ever more vital that we incorporate them into our understanding of ecology. To this end, we added heat waves into a classic theoretical model of a plant-herbivore interaction. We used the model to explore how plant-herbivore dynamics vary with (1) the seasonal timing of heat waves and (2) the mechanisms by which heat waves influence plant and herbivore physiology. Finally, we exposed two milkweed species (Asclepias spp.) to brief periods of extreme heat at varied times during ontogeny and measured plant and insect performance and growth.
Results/Conclusions
The theoretical model indicated that the effects of heat wave events on the dynamics of plant-herbivore interactions depended on an interaction between (1) the timing of heat waves relative to plant and herbivore ontogeny and (2) the mechanisms by which heat waves influenced plant and herbivore physiology. In situations where heat waves increased the strength of induced plant defenses, heat waves early within a season had the strongest negative effects on herbivore density. In situations where heat waves directly reduced plant quality, heat waves late within a season had the strongest negative effects on herbivore density. Our results indicate that even though heat waves are brief events in the lives of plants and insects, their physiological effects are likely to scale up to alter long-term population dynamics.