Research | Dave's Research Site

Research Themes

Summary: My research investigates the ecological consequences of stressors arising from global environmental change. Stressors, from extreme weather to infectious disease, afflict wild animals as they do humans. Even when stressful events are not catastrophic, they cause changes organisms to change tehir behavior and physiology in ways that can be costly to health, survival, and fitness (think of how COVID changed our behavior and physiological stress levels). For now, wild animal populations may be surviving with global change stressors, but are they thriving? This question has not received scientifically answers, leaving substantial uncertainty over the future of Earth's biodiversity.

Wildlife Infectious Disease

The majority of my research has investigated stress in the context of parasitism. Parasites threaten homeostasis and thus act as stressors. Amphibians and the fungal parasite Batrachochytrium dendrobatidis (Bd) were a powerful case study in how a stressor interacts with host ecology at the levels of organisms, populations, and communities. Bd is the causal agent of the disease chytridiomycosis, a main driver of global amphibian declines that has caused more species losses than any other known parasite. My studies of Bd contributed a body of literature on interactions between host movement and infection risk, the community ecology of parasitism, and conservation of rare species.

Research Framework. My studies link organism-level stress responses to population- and community- level processes through interdisciplinary work that combines field studies, laboratory experiments, genomics and modelling.

Spiny Common Toads (Bufo spinosus) in amplexus while being radio-tracked to monitor their disease status.

Sierra de Guadarrama, Central Spain, 2009.

The Ecology of Fear

Ecologists have long recognized that

predators, humans, and other biological

stressors elicit so-called ‘fear’ – avoidance

of perceived threats – in wild animals and

that fear alone can have non-lethal

behavioral and physiological effects, with

downstream consequences to fitness,

population demography, and community structure. My research investigates ecological impacts of fear in the context of parasitism, predation, and human disturbance. I am currently developing epigenetic assays to characterize the lifetime health and fitness consequences of living chronically in states of fear.

Endangered species conservation

My research at UCLA is investigating the extent to which multiple stressors impact threatened Yosemite toads (Anaxyrus canorus) in Yosemite National Park, in coordination with the Yosemite Aquatic Resources Team. We have been quantifying risk of Bd infection in toads, and the data indicate that (a) infection risk varies across toad life stages; juveniles are the most susceptible, and (b) significant Bd transmission occurs during toad hibernation. I am building on this disease-oriented research by developing DNA methylation assays for examining cumulative stress in toads, from disease as well as other stressors (e.g. drought).

Adult female Yosemite toad (Anaxyrus canorus).