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 all organisms, and much of organismal biology is shaped by interactions with stressors. I have a particular interest in non-lethal effects of stressors on animal behavior, physiology, and fitness.

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 and mathematical modelling

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, I am quantifying risk in toads to inform planned re-introductions. Infection data from systematic Bd surveillance indicate that (a) infection risk varies across toad life stages; juveniles are the most susceptible, and (b) significant Bd transmission occurs during toad hibernation. This research is informing an NPS recovery plan for Yosemite toads and a grant proposal for test mechanisms of Bd transmission during hibernation.

Adult female Yosemite toad (Anaxyrus canorus).