Systematic shifts in the variation among host individuals must be considered in climate-disease theory

Abstract

AbstractTo make more informed predictions of host-pathogen interactions under climate change, studies have incorporated the thermal performance of host, vector, and pathogen traits into disease models. However, this body of work has ignored the fact that disease spread and long-term patterns of host population dynamics are largely determined by the variation in susceptibility among individuals in the host population. Furthermore, and especially for ectothermic host species, variation in susceptibility is likely to be plastic, influenced by variables such as environmental temperature. Quantifying the relationship between temperature and among-host trait variation will therefore be critical for predicting how climate change and disease will interact to influence host-pathogen population dynamics. Here, we demonstrate how short-term effects of temperature on the variation of host susceptibility drive epidemic characteristics, fluctuations in host population sizes, and probabilities of host extinction. We use this quantitative analysis as a basic framework to suggest that more research is needed in disease ecology to understand the mechanisms that shape trait variation, not just trait averages.