Environmental refuges from disease in host–parasite interactions under global change

Abstract

The physiological performance of organisms depends on their environmental context, resulting in performance–response curves along environmental gradients. Parasite performance–response curves are generally expected to be broader than those of their hosts due to shorter generation times and hence faster adaptation. However, certain environmental conditions may limit parasite performance more than that of the host, thereby providing an environmental refuge from disease. Thermal disease refuges have been extensively studied in response to climate warming, but other environmental factors may also provide environmental disease refuges which, in turn, respond to global change. Here, we (1) showcase laboratory and natural examples of refuges from parasites along various environmental gradients, and (2) provide hypotheses on how global environmental change may affect these refuges. We strive to synthesize knowledge on potential environmental disease refuges along different environmental gradients including salinity and nutrients, in both natural and food‐production systems. Although scaling up from single host–parasite relationships along one environmental gradient to their interaction outcome in the full complexity of natural environments remains difficult, integrating host and parasite performance–response can serve to formulate testable hypotheses about the variability in parasitism outcomes and the occurrence of environmental disease refuges under current and future environmental conditions.

A framework for understanding climate change impacts through non‐compensatory intra‐ and interspecific climate change responses

“…As predator feeding rates are increasing functions of prey densities, lower prey densities could feedback to lower predator feeding rates One impetus for the development of the framework herein was that there is often a disconnect in the literature between traits measured and their inferred effects on downstream climate change responses of interest. For example, differences among species in thermal performance curve properties are often used to suggest the existence of differential responses to temperature that will impact the system (Cohen et al, 2017;Gsell et al, 2023;Meehan & Lindo, 2023).…”

“…One impetus for the development of the framework herein was that there is often a disconnect in the literature between traits measured and their inferred effects on downstream climate change responses of interest. For example, differences among species in thermal performance curve properties are often used to suggest the existence of differential responses to temperature that will impact the system (Cohen et al., 2017; Gsell et al., 2023; Meehan & Lindo, 2023). Yet, applying the framework here, it becomes clear that the relevance of differences in thermal performance curves and whether they lead to non‐compensatory climate change effects is dependent on what trait is being compared among species, where the response of interest occurs within the rate hierarchy, and how ‘performance’ at that position in the rate hierarchy translates to the downstream rate of interest.…”

A mechanistic framework of enemy release

“…Temporal or spatial asynchronicity between exotic plants and their potential enemies affects the diversity of enemies that accumulate (Gsell et al., 2023). Temporally, exotic species can benefit from ‘invasion windows’ if generalist enemies are less abundant in a given season (Agrawal et al., 2005; Geppert et al., 2021).…”

A framework for understanding climate change impacts through intra- and interspecific asymmetries in climate change responses

“…One impetus for the development of the framework herein was that there is often a disconnect in the literature between climate change responses used to infer asymmetries and their effects on systems and the climate change response itself. For example, given the ubiquity of thermal performance curves, differences among species in thermal performance are often used to suggest the existence of asymmetries that will impact the system (Cohen et al 2017;Gsell et al 2023;Meehan & Lindo 2023). Yet, applying the framework here, it becomes clear that the relevance of differences in thermal performance curves for asymmetries is dependent on what metric of performance is being compared among species, where in the rate hierarchy the asymmetry of interest occurs, and how 'performance' translates to the downstream rate of interest.…”