Main Research Themes
A brief presentation of my work, made for the Institute of Public Health at Washington University of St. Louis. March, 2020.
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. Wildlife are no different. Wildlife move farther and more frequently than once thought, and their movement patterns are shifting with globalization and climate change. With emergence of novel pathogens on the rise, more complete characterization of wildlife movement and its impact on disease risk can 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, and perhaps the largest contributor to global biodiversity losses in general. 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 sought out those upland habitats when they contracted infections. In addition to spreading parasites, movement can therefore protect hosts from their detrimental effects. My research program is now developing ways to utilize the protective benefits of movement to conserve endangered species threatened by disease.
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 to many organisms. 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.
This work takes non-lethal effects of predators and parasites into account as well. Predators and parasites impose a wide array of non-lethal effects, including their influence on movement patterns of their prey and hosts. 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, although both predators and parasites cause non-lethal effects, those effects differ in timing and magnitude (See figure, below).
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 (red boxes) until later stages of interactions, when parasites already infect and feed on them.