research team mentor

Research focus for summer 2025

Our research group seeks to understand how environmental variation affects the ecology and evolution of infectious diseases, and how diseases can impact the ecosystems in which they occur. We use common weedy plants (Plantago species) and their fungal pathogens (powdery mildews) as a model system for investigating environment-disease interactions.

Important questions we ask include:

• How does large-scale latitudinal variation in winter climate drive variation in the prevalence and diversity of fungal parasites?

• How does variation in land use context (e.g., urban, suburban, rural) and microhabitat (e.g., shade) affect plant population ecology and plant-pathogen interactions?

• How do parasites affect flows of energy and nutrients through food webs and alter ecosystem processes?

This summer, our team will focus on two projects at Tyson Research Center:

• Ecological and evolutionary consequences of climate warming for fungal pathogens: Environmental change is expected to impact the risk of disease for plants and wildlife worldwide. Predicting those impacts requires understanding the role of climate in determining when and where diseases can occur. Understanding how climate affects pathogen evolution is also essential for improving disease prediction and management. Fungal pathogens cause many diseases that threaten hosts of agricultural and conservation concern. However, effects of environmental change on fungal pathogens are poorly understood. This is largely because fungi have complex life cycles that are challenging to study with respect to climate. For example, many fungi reproduce in different ways under different climate conditions. In one of the research gardens at Tyson Research Center, we will perform a common garden field experiment to quantify effects of climatic variables (temperature, humidity, light) on the development of asexual and sexual stages of powdery mildew on Plantago host plants. We will grow plants from seeds collected along a latitudinal gradient in the central United States, and transplant those seedlings into the research garden. Then, we will establish microclimate treatments using shade cloth and inoculate all plants with powdery mildew strains collected from wild plants at Tyson. Over the course of the summer, we will measure several plant traits as well as the development of powdery mildew infection. Members of the Penczykowski lab will continue collecting data on this experiment over the following fall, winter, and spring.

• Climate and connectivity as drivers of pathogen dynamics within and between urban plant populations: Urban life presents many challenges for animals and plants. Roads and buildings divide the landscape into small patches of vegetation in parks, yards, and gardens. Species in those habitats are in close contact with humans and vehicles. Cities also produce and trap more heat than surrounding areas. Habitat fragmentation, human activity, and warming can each impact the risk of disease for organisms. However, it is unknown how these factors alter the spread of disease in urban systems. This knowledge gap hinders prediction and management of disease for urban wildlife and plants. To fill this gap, our lab is using a combination of mathematical models, field studies, and experiments. This summer, our Tyson team will perform monthly surveys of Plantago populations in parks along an urbanization gradient in the St. Louis region. This will be our 6th year of data collection at those sites, so we are learning about drivers of year-to-year variability in the plant populations and their rates of powdery mildew infection. In addition, we will conduct a common garden experiment in raised garden beds at multiple sites along the urbanization gradient. That experiment will be similar to the field experiment described above, except that it is replicated at different urban, suburban, and rural sites (including a garden bed at Tyson), and the plants will be grown from seeds collected in urban, suburban, and rural sites in the St. Louis region. Some of the sites of this garden experiment are schools in the School District of University City, where we have opportunities with engagement with members of those school communities.

Skills
techniques
methods

Members of our team will work together to carry out multiple projects investigating environment-disease interactions, and we seek a group of students with diverse backgrounds, interests, and personalities. Students on our team can expect to develop a suite of skills in observational and experimental field research, data analysis, and teamwork, and will receive training and mentoring including in the following areas:

• Field surveys

  • Identification of common weedy plants and their fungal pathogens

  • Vegetation survey techniques

  • Use of a Robotany automated aerial imaging apparatus to take high-resolution photographs of replicate 1 x 1 m field plots in each site

• Field experiments

  • Manipulation and measurement of key environmental variables (e.g., temperature, humidity, and light levels)

  • Methods for inoculating plants with powdery mildew

  • Measurement of plant traits including leaf size, flower development stage, and severity of damage from disease and herbivory

• Data collection, management, and analysis

  • Best practices for documentation in field and lab notebooks and datasheets

  • Best practices for data entry and curation in Excel

  • Data analysis using R

• Teamwork and communication skills