I am broadly interested in the ecology and evolution of host–parasite interactions, and how such interactions both affect and are affected by the abiotic and biotic context in which they occur (Fig. 1). My research involves a combination of observational studies of natural populations and communities, manipulative experiments in the field and lab, and mathematical models. I have employed these complementary approaches to study host–parasite interactions in both aquatic and terrestrial ecosystems, and my current research focuses on wild populations of herbaceous plants (e.g., Plantago lanceolata, Fig. 2) and their pathogens.
Figure 1. Schematic illustrating the potential for feedbacks between ecosystems and disease. Environmental and ecological context can shape host–parasite interactions, and parasite epidemics can in turn alter the structure and function of ecological communities and ecosystems.
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 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 evolution of hosts and parasites affect epidemiological dynamics?
Figure 2. (A) Plantago lanceolata (common names include ribwort plantain and narrowleaf plantain) in a dry meadow. A white paper tag marks the center of an individual P. lanceolata rosette. (B) Close-up photograph of P. lanceolata leaves infected with the powdery mildew pathogen Podosphaera plantaginis.
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.