Ecology of Emerging Infectious Disease
In the last few years, a newly identified fungal pathogen, Batrachochytrium dendrobatidis, causing the disease chytridiomycosis, poses a new threat to the amphibians. As a postdoctoral scholar with Dr. Cherie Briggs and colleagues, I have investigated the dynamics of this emerging pathogen mainly in the Sierra Nevada, California but have also recently begun collaborative work in Mexico and Guatemala. My primary role in the Sierra Nevada is to provide empirical data on the ecology of a host species, the mountain yellow-legged frog (Rana muscosa). During my dissertation and continuing to the present, I have studied the phylogeography, genetics, breeding behavior, growth, and movement dynamics of this species. My colleagues and I have incorporated many of these data into a stage structured disease model that may help predict spread of the pathogen in the wild. We have also documented the catastrophic impact of the disease on natural populations. To better understand the dynamics of the disease, I have investigated transmission of the fungal pathogen between life stages of the host and I am very interested in how behavior may affect transmission. Like many other emergent diseases, little is known about the origin of B. dendrobatidis and there is considerable debate whether it is a novel pathogen or a newly virulent strain. My research on this disease takes place mostly in field settings, but also in the lab. Currently I am tracking the spread of the disease in remote areas of the Sierra Nevada. Interestingly, some populations of frogs are going extinct after chytridiomycosis outbreaks while others survive. The outcome of my current research will help shape recovery efforts for threatened host species, will help inform models for this disease, and will also help with our general understanding of disease ecology.
Food webs at the aquatic / terrestrial boundary
In collaboration with Dr. Jacques Finlay (Univ. Minnesota), I have been studying the effects of introduced trout on aquatic food webs in the high elevation Sierra Nevada. In particular, we have used a combination of techniques (stable isotopes, insect emergence traps and consumer mark-recapture) to track linkages between terrestrial and aquatic productivity. The introduction of non-native trout in this system has decreased energy flow across the terrestrial aquatic boundary, decreasing food availability for many terrestrial consumers, including R. muscosa. Our work promises to increase our general understanding of the linkages between terrestrial and aquatic systems.
Doctoral research
My doctoral dissertation at the University of California Berkeley was focused on an assemblage of amphibian species that occur in well-protected wilderness areas of the Sierra Nevada, California. This mountain range contains some of the largest contiguous tracts of roadless land in the USA, yet some amphibian species have disappeared while other species, occupying the same habitat, remain abundant. The problem is not restricted to California; amphibian declines are occurring in protected areas worldwide and have captured the attention of the scientific community as well as the general public. Using a combination of field and laboratory experiments, my dissertation examined two potential stressors on amphibians: 1) introduced trout, and 2) increased levels of ultraviolet radiation (UV-B). I found strong negative effects of introduced trout and no effects of UV-B. My dissertation work continues to be relevant to my growing interests in emerging infectious diseases, behavior and conservation.
Research
