Main Research Themes
A brief presentation of my work, made for the Institute of Public Health at Washington University of St. Louis. March, 2020.
Host Movement and Infection Risk: My research investigates how movement affects disease risk. The COVID-19 pandemic makes brutally clear how movement can facilitate the spread of harmful pathogens. It also highlights how much of our normal lives is spent on the move. Whether to buy food or to meet friends, a lot of our time is spent in transit from one location to another. The same goes for wildlife. Advances in wildlife tracking have revealed that wildlife move farther and more frequently than once thought. With the emergence of novel pathogens on the rise, better characterization of wildlife movement and its impact on disease risk is urgently needed to address outstanding threats to biodiversity and global health.
I study this topic in amphibians and the devastating fungal pathogen Batrachochytrium dendrobatidis (Bd). Bd is the causal agent of the disease chytridiomycosis, a main driver of global amphibian declines, which has now caused more species losses than any other parasite known. While tracking toads in Spain, I found that individuals recover from Bd infections when migrating to terrestrial shelters. Videotaping newt movements (See photo, below right) showed that individuals were more likely to recover from Bd infections while in the upland habitats through which they move. Further, individuals actively sought upland habitats when they contracted infections. This body of work emphasizes that, in addition to spreading parasites, movement can protect hosts from their detrimental effects.
Multi-trophic Disease Dynamics: Real ecosystems contain multiple consumers that feed on the same organisms. Parasites such as bacteria, viruses, and fungi co-infect single organisms and interact inside them. Predators often feed on the same organisms that parasites infect, and parasites are themselves prey. My research is building a framework for understanding these more complex, yet more realistic, interactions between parasites, predators, and their shared resources. Again, movement plays a central role in this work. My current project at the National Great Rivers Research and Education Center is building large, high-resolution datasets of salamander and frog movement to understand their predator-prey dynamics. An experiment at the Zoological Society of London tested how newt movement in different habitats mediate interactions between aquatic invertebrates that eat Bd spores.
This work also takes non-lethal effects of predators and parasites into account. Predators and parasites impose a wide array of non-lethal effects. Avoidance of foraging habitats to reduce contact with predators or infective parasite stages is a common example. A recent synthesis of the literature showed that while both predators and parasites cause non-lethal effects, they differ in when and how strongly those effects are imposed (See figure, below). My future work will test how these distinct non-lethal effects alter patterns of animal movement, and in turn, impact the spread of disease.
An automated imaging system constructed at the Institute of Zoology, Zoological Society of London
In contrast to amphibian responses to predators (blue box), individuals do not respond to parasites until later stages of interactions, when parasites already infect and feed on them.