​Current projects:

The effects of climate change on the evolution and epidemiology of plant pathogens

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Team Flax 2020: (L to R) Juliana Jiranek, Sarah Coffey, Ian Miller, Maria Stahl, and Barrett Gray



​The potential for climate change to exacerbate the burden of human infectious diseases has been increasingly recognized, but less attention has been given to the effects of climate change on infectious diseases of plants. Plant pathogens are critical components of natural ecosystems, and also pose a serious threat to agricultural production and food security, reducing the yield of major crops by about 20% each year. I use a wildflower native to the Rocky Mountains (Lewis flax, Linum lewisii) and its fungal pathogen (flax-rust, Melampsora lini) to study how climate change might affect the evolution and epidemiology of plant pathogens. The natural gradient of temperature and humidity that occurs down the slope of the mountains on which my study species occur serves as a proxy for climate change.

The aims of this project are to 1) determine how environmental factors affect transmission dynamics of flax rust from the scale of a single leaf to the scale of a population, and 2) to characterize the link between qualitative and quantitative virulence (i.e. infectivity and aggressiveness) and predict how climate change might shift the evolutionary limits to these traits in plant pathogens.

This work is being carried out in partnership with the Rocky Mountain Biological Laboratory (RMBL), and is supported by the Princeton Environmental Institute, the Princeton Center for Health and Wellbeing, and RMBL.
Click here to watch a Rocky Mountain Biological Laboratory 'Lab Chat' about the flax-rust project.

COVID-19 Morbidity and Mortality




​At the beginning of the pandemic, I estimated the distribution of COVID-19  burden in the U.S., finding that rural regions might be hit the hardest due to their older populations and limited access to healthcare. I have also been involved in projects quantifying the impact of pharmaceutical intervention and investigating variation in the spread of disease in sub-Saharan Africa.

Host heterogeneity, Virulence Evolution, and Vaccination


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This current project deals with how pathogens adapt to heterogeneity in host immunity. I'm currently focusing on problems related to pertussis and COVID-19 vaccines.

Past projects:

Evaluating the Uniqueness of Human Life History Techniques with Phylogenetic Comparative Methods


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I applied advanced phylogenetic comparative methods to primate life history data to evaluate whether humans are truly exceptional in terms of their life history traits and various brain traits. 

Infectious Disease and the Evolution of Plant Sexual Systems



Infectious disease can impose a strong selective force, especially when its fitness costs to hosts are high. This is the case in the anther smut system, where the fungus Microbotryum violaceum completely sterilizes its host, Dianthus pavonius. I investigated sex-based differences in disease avoidance in this system, and showed theoretically how such differences can drive the evolution of sexual systems.