Local demographic and epidemiological patterns in the Linum marginale – Melampsora lini association – a multi-year study

1.Many theoretical and empirical studies operate from an assumption that pathogens have a significant influence on the fecundity and lifespan of their host species. However, there is surprisingly little data investigating the long-term fitness impacts and genetic consequences that arise from pathogen infection in natural populations. Here, we address this gap through the analysis of a dataset investigating the local population dynamics of a native host plant (Linum marginale) and an associated rust pathogen (Melampsora lini) across 12 years.

2.To investigate patterns of disease prevalence and severity and track effects on host fecundity and demography we conducted censuses on an annual basis at a single site. Annual M. lini infection prevalence ranged from 0% to 99%. Severe epidemics occurred in 3-4 year cycles causing high overwintering mortality and subsequent changes in the relative abundance of different host phenotypes. Host population size oscillated in response to epidemics an...