Co‐evolutionary hot and cold spots of selective pressure move in space and time

Summary 1. A long‐term study (19 years) of a host–pathogen metapopulation involving 133–220 separate populations of the wild plantFilipendula ulmariaand its rust pathogenTriphragmium ulmariaeshows marked changes in the occurrence (32–55% demes) and severity of disease and rates of extinction and re‐establishment of individual populations (0.006–0.174 and 0.030–0.195 per annum, respectively) over time. 2. Modelling of the spatio‐temporal dynamics of disease demonstrated year‐to‐year changes associated with a range of different environmental features, but also more consistent, longer‐term patterns influenced by a complex suite of factors. 3. Both the level of disease and its spatial location varied through time and generated a changing pattern of selective pressure across the metapopulation. 4. Synthesis. Our results suggest that co‐evolutionary hot spots and cold spots can be highly dynamic within metapopulations, thereby fuelling the co‐evolutionary process even more than previously suspected.