Rachel Penczykowski

Assistant Professor of Biology
PhD, Georgia Institute of Technology
research interests:
  • Host-Parasite Interactions
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    contact info:

    mailing address:

    • Washington University
    • CB 1137
    • One Brookings Drive
    • St. Louis, MO 63130
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    Rachel Penczykowski is broadly interested in the ecology and evolution of host–parasite interactions, and how ecological context affects the risk of infection and consequences of disease for hosts. 

    Penczykowski's research involves a combination of observational studies of natural populations and communities, manipulative experiments in the field and lab, and mathematical models. She has employed these complementary approaches to study host–parasite interactions in both aquatic and terrestrial ecosystems, and her current research focuses on wild populations of herbaceous plants and their pathogens. 

    Her research themes include:

    1. Effects of abiotic and biotic context on host-parasite interactions

    How do physical and chemical features of the environment, as well as the broader community of organisms living there, affect the risk of infection and consequences of disease for hosts?

    What are the implications of human-driven changes in climate, land use, and biodiversity for host-parasite interactions?

    2. Indirect effects of parasitism on communities and ecosystems

    Do changes in the density or traits of infected hosts affect other members of the ecological community, altering flows of energy and nutrients through the food web? 

    Can feedback loops occur in which the effects of disease on ecosystems subsequently alter epidemiological dynamics (Fig. 1)?

    3. Eco-evolutionary dynamics of host-parasite interactions

    How does ecological context affect the (co)evolutionary dynamics of hosts and parasites?

    Over what spatial and temporal scales does the evolution of hosts and parasites affect epidemiological dynamics? 

    Selected Publications

    Parratt SR, Barrés B, Penczykowski RM, and Laine A-L. Local adaptation at higher trophic levels: Contrasting hyperparasite-pathogen infection dynamics in the field and laboratory. Molecular Ecology. In press.

    Strauss AT, Shocket MS, Civitello DJ, Hite JL, Penczykowski RM, Duffy MA, Cáceres CE, and Hall SR. 2016. Habitat, predators, and hosts regulate disease in Daphnia through direct and indirect pathways. Ecological Monographs, 86: 393–411.

    Hite JL, Penczykowski RM, Shocket MS, Strauss AT, Orlando PA, Duffy MA, Cáceres CE, and Hall SR. 2016. Parasites destabilize host populations by shifting stage-structured interactions. Ecology, 97:439-449.

    Penczykowski RM, Laine A-L, and Koskella B. 2016. Understanding the ecology and evolution of host-parasite interactions across scales. Evolutionary Applications, 9:37–52.

    Civitello DJ, Penczykowski RM, Smith A, Shocket MS, Duffy MA, and Hall SR. 2015. Resources, key traits, and the size of fungal epidemics in Daphnia populations. Journal of Animal Ecology, 84:1010-1017.

    Penczykowski RM, Walker E, Soubeyrand S, and Laine A-L. 2015. Linking winter conditions to regional disease dynamics in a wild plant-pathogen metapopulation. New Phytologist, 205:1142-1152.

    Penczykowski RM, Lemanski BCP, Sieg RD, Hall SR, Housley Ochs J, Kubanek J, and Duffy MA. 2014. Poor resource quality lowers transmission potential by changing foraging behavior. Functional Ecology, 28:1245-1255.

    Penczykowski RM, Hall SR, Civitello DJ, and Duffy MA. 2014. Habitat structure and ecological drivers of disease. Limnology & Oceanography, 59:340-348.

    Auld SKJR, Penczykowski RM, Housley Ochs J, Grippi DC, Hall SR, and Duffy MA. 2013. Variation in costs of parasite resistance among natural host populations. Journal of Evolutionary Biology, 26:2479-2486.

    Civitello DJ, Penczykowski RM, Hite JL, Duffy MA, and Hall SR. 2013. Potassium stimulates fungal epidemics in Daphnia by increasing host and parasite reproduction. Ecology, 94:380-388.

    Duffy MA, Housley Ochs J, Penczykowski RM, Civitello DJ, Klausmeier CA, and Hall SR. 2012. Ecological context influences epidemic size and parasite-driven evolution. Science, 335:1636–1638. 

    Duffy MA, Housley JM, Penczykowski RM, Cáceres CE, and Hall SR. 2011. Unhealthy herds: indirect effects of predators enhance two drivers of disease spread. Functional Ecology, 25:945–953.

    Penczykowski RM, Forde SE, and Duffy MA. 2011. Rapid evolution as a possible constraint on emerging infectious diseases. Freshwater Biology, 56:689-704.