In the face of climate change, it is important to develop better models describing how temperature influences species interactions such as parasitism. However, the outcome of parasitism depends on the interaction of distinct yet inherently confound physiological responses from each species – parasite infectivity and host resistance - which can be difficult to disentangle. The metabolic theory of ecology (MTE) provides a possible solution to this problem. One of the fundamental predictions of MTE is that metabolic parameters are broadly shared across species and physiological processes.. If this prediction is true for physiological processes within the same organism, it could allow key model parameters to be estimated by measuring metabolic performance separately for the host and the parasite. Here we developed a series of models based on MTE describing temperature-dependence of interactions between the trematode Ribeiroia ondatrae and Lithobates clamitans (green frog) tadpoles. We parameterized this model by measuring separate non-linear thermal performance curves for host and parasite metabolisms, including thermal acclimation effects, and applied the model to predict effects of temperature and thermal acclimation on parasite encystment and cyst clearance.
The activation energy for host metabolism was the parameter most affected by thermal acclimation, and there was a striking non-linearity in thermal acclimation effects on cyst clearance that matched a similar pattern in acclimation effects on tadpole respiration, These results suggest that key model parameters are indeed similar across physiological processes within a species, as predicted by MTE, making this a potentially powerful approach to modeling the temperature-dependence of species interactions like parasitism.