Disease ecology meets ecological immunology: understanding the links between organismal immunity and infection dynamics in natural populations

P>1. Ecological immunology and disease ecology are two relatively young disciplines that apply ecological approaches and principles to traditionally non-ecological fields. In both cases, an ecological perspective has allowed new insights to emerge by focusing attention on variation over space and time, and by emphasizing the role of the environment in shaping individual responses and the outcome of host-pathogen interactions. Here we review the growing conceptual interface between these two rapidly evolving fields. 2. Areas of synergy between ecological immunology and disease ecology aim to translate variation in within-host processes (e.g. immunity) into between-host dynamics (e.g. parasite transmission). Emerging areas of synergy include potential immune mechanisms that underlie host heterogeneity in disease susceptibility, teasing apart the effects of environmental factors such as seasonality and climate on host susceptibility and pathogen dynamics, and predicting the outcome of co-infection by functionally distinct groups of parasites that elicit different immune responses. 3. In some cases, practical limitations have constrained the merging of ideas in ecological immunology and disease ecology. We discuss several logistical challenges, including dissecting the relative roles of host exposure and susceptibility, establishing links between measures of immunity and pathogen resistance in wild populations, and incorporating relevant immune variation into prevailing disease ecology modeling frameworks. 4. Future work at the interface of these two fields should advance understanding of life-history theory, host-pathogen dynamics, and physiological ecology, and will also contribute to targeted approaches for wildlife health and zoonotic disease prevention.