Flipping through field notebooks…
Infectious diseases vary in severity across time and space. This variation makes it difficult to forecast epidemics, so there is a need to describe the underlying factors that contribute to diverse disease outcomes across populations. A growing body of work attests to the role of environmental context in shaping epidemics. At the most basic level, environment can alter host and pathogen physiology and landscape distribution. These changes could cascade to affect host and pathogen evolution by altering selection, leading to different coevolutionary trajectories across environments. However, there are few model systems where ecological measures of disease prevalence and severity across environments can be integrated with genetic data to test hypotheses about how ecological context shapes host evolution. Established in 2018, the Flax Rust Project leverages the powerful system of Lewis flax (Linum lewisii), a supalpine wildflower abundant on the slopes near RMBL, and flax rust (Melampsora lini), its conspicuous fungal pathogen. Populations occur across a steep elevational gradient, allowing the measurement of a wide variety of weather conditions that contribute to the spread of disease. Through long-term observation of disease transmission in study populations, we investigate how hosts balance adaptation to both their abiotic environment and their pathogens. Lewis flax is also a burgeoning model system in genomics, so we can further integrate field measurements of disease with genetic information about our study populations to investigate the role of disease in molecular evolution of this host. Understanding the impacts of environment on epidemics and host evolution will shed light on how disease might be expected to shift as the climate warms and whether we expect hosts to adapt to changing pressures.