Resource limitation determines realized thermal performance and the
potential for metabolic meltdown.
Abstract
1) As temperatures rise across the globe, many species may approach or
even surpass their physiological tolerance to withstand high
temperatures. Thermal performance curves, which depict how vital rates
vary with temperature, are often measured under ideal laboratory
conditions and then used to determine the physiological or demographic
limits of persistence. However, this approach fails to consider how
interactions with other factors (e.g. resources, water availability) may
buffer or magnify the effect of temperature change. Recent work has
demonstrated that the breadth and shape of a consumer’s thermal
performance curve change with resource densities, highlighting the
potential for temperature interactions and leading to a potential
‘metabolic meltdown’ when resources decline during warming (Huey and
Kingsolver 2019). 2) Here, we further develop the basis for the
interaction between temperature and resource density on thermal
performance, persistence, and population dynamics by analyzing
consumer-resource dynamic models. We find that the coupling of consumer
and resource dynamics relaxes the potential for metabolic meltdown
because a reduction in top-down control of resources occurs as consumers
approach the limits of their thermal niche. However, when both consumers
and resources have vital rates that depend on temperature, asymmetry
between their responses can generate the necessary conditions for
metabolic meltdown. 3) Moreover, we define the concept of a ‘realized’
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. 4)
Synthesis. A better understanding of the link between temperature
change, species interactions, and persistence allows us to improve
forecasts of community response to climate change. Our work elucidates
the importance of thermal asymmetries between interacting species, and
resource limitation as a key ingredient underlying realized thermal
niches.