Interactions between consumer thermal performance and resource limitation yield insight into the shape and structure of realized thermal performance curves

Background/Question/Methods

As temperatures rise across the globe, many species may approach or even surpass their physiological tolerances to withstand high temperatures. Thermal performance curves, often measured under ideal laboratory conditions, are commonly used to determine the physiological or demographic limits of persistence (Tmin and Tmax); however, this approach fails to consider how interactions with other factors (e.g. resources, water availability) may buffer or magnify the effect of warming. Recent work has demonstrated that the breadth and shape of a consumer’s thermal performance curve changes with resource densities, highlighting the potential for interactions and leading to a potential ‘metabolic meltdown’ when resources decline during warming (Huey & Kingsolver, 1989). Here, we further develop understanding of the interaction between temperature and resource density on thermal performance, persistence, and population dynamics by analyzing a pair of consumer-resource dynamic models.

Results/Conclusions

We find that the coupling of consumer and resource dynamics relaxes the potential for metabolic meltdown via a reduction in top-down control of resources as consumers approach Tmax. However, we also show that when both consumers and resources have vital rates that depend on temperature, asymmetry between their responses can generate the necessary conditions for metabolic meltdown. Last, we define the concept of an ‘operational’ thermal performance curve that takes into account the dynamic interaction between consumers, resources and temperature, and we describe an important role for this concept moving forward.