Theory of temperature-dependent consumer-resource interactions

Abstract

Changes in temperature affect consumer-resource interactions which underpin the functioning of ecosystems. However, existing studies report contrasting predictions regarding the impacts of warming on biological rates and community dynamics. To improve prediction accuracy and comparability, we develop a framework that combines two approaches: sensitivity analysis and aggregate parameters. The former determines which biological parameters impact the community most strongly. The use of aggregate parameters (i.e., maximal energetic efficiency, ρ, and interaction strength, κ), that combine multiple biological parameters, increases explanatory power and reduces the complexity of theoretical analyses. We illustrate the framework using empirically-derived thermal dependence curves of biological rates and applying it to consumer-resource biomass ratio and community stability. Based on our analyses, we present four predictions: 1) resource growth rate regulates biomass distributions at mild temperatures, 2) interaction strength alone determines the thermal boundaries of the community, 3) warming destabilises dynamics at low and mild temperatures only, 4) interactions strength must decrease faster than maximal energetic efficiency for warming to stabilise dynamics. We argue that directly measuring the aggregate parameters should increase the accuracy of predictions on warming impacts on food webs and promote cross-system comparisons.

Thermal plasticity and evolution shape predator–prey interactions differently in clear and turbid water bodies

“…The stability metric, 𝒮, defines stability in relation to the Hopf bifurcation (i.e. the point at which the population dynamics switch from stable equilibria to limit cycles; Synodinos et al, 2021)𝒮 > 0 corresponds to a stable equilibrium and 𝒮 < 0 to oscillations. Hence, larger values of 𝒮 indicate a more stable system.…”

“…To estimate the stability of the predator–prey system, we applied a stability metric that quantifies the tendency of the predator and prey population densities to oscillate around the equilibrium points (Synodinos et al, 2021). The stability metric, 𝒮, defines stability in relation to the Hopf bifurcation (i.e.…”

“…Despite its importance, much less is known about the effects of warming and turbidity on the long‐term stability of the predator–prey system, which can be defined as the tendency of the predator and prey population densities to oscillate around the equilibrium densities (Pimm, 1984; Synodinos et al, 2021). These effects will not only depend on changes in the functional response parameters, but also parameters relevant for the population dynamics such as the predator metabolic rate and the prey’s carrying capacity.…”

Resource limitation determines realized thermal performance of consumers in trophodynamic models

“…The temperature‐scaling of these parameters can be jointly, or individually determined by the resource or consumer's traits. A key challenge for incorporating thermal mismatch into trophodynamic models is understanding which model elements scale with temperature and how we might reasonably constrain the number and type of mismatches that can arise amongst the various model parameters (Amarasekare, 2015; Dell et al, 2014; Synodinos et al, 2021; Vasseur, 2020).…”

Energetic mismatch induced by warming decreases leaf litter decomposition by aquatic detritivores

“…In this context, energy‐based models provide a powerful framework to explore the consequences of global warming for consumer–resource dynamics by incorporating empirical physiological traits of individuals associated with changes in body mass and temperature into modelling simulations of population and community dynamics. Significant advances on thermal bioenergetic models have been done over the past decades (Gilbert et al, 2014; Rall et al, 2010; Synodinos et al, 2021; Vasseur & McCann, 2005) and recent studies extended the previous assumptions by including a temperature‐driven change in body mass (Bernhardt et al, 2018; Osmond et al, 2017; Sentis et al, 2017), making these models a relevant approach for studying the impacts of temperature and body size changes on detritivore–resource dynamics. One key finding emerging from these modelling studies is that investigating the balance between key physiological processes that determines the fitness of detritivores (Jabiol et al, 2020) is crucial to better predict the responses of populations and freshwater ecosystems to global warming (Bideault et al, 2020; Demars et al, 2011; Yvon‐Durocher et al, 2010).…”