Research
I. NEOTROPICAL AMPHIBIAN ECOLOGY
My research interests center on field ecology, population demography, and the evolution of life histories of anurans and reptiles. I am particularly interested in determining the spatiotemporal variation in diversity and abundance of amphibians and reptiles in various communities, studying comparative population demography of tropical stream frogs, and quantifying the role of adult and larval amphibians in tropical and temperate ecosystems. Most of my recent fieldwork involves studies of amphibian population declines, especially those of the Neotropics. Most of my research and that of my lab focuses on comparative ecology of these diverse tropical faunas with the goal of using these data to understand differential patterns of decline.
A. Host-pathogen Ecology
Most recently, I have been working on determining the geographic and ecological patterns of amphibian declines in Latin America following several die-offs of wild amphibians at multiple sites. By analyzing patterns of decline among species and across many sites, we hope to predict future declines of other populations at other sites and to prioritize research and conservation actions. In Latin America, amphibian populations have suffered tremendous losses, many of which were apparently caused by disease from an aquatic frog-killing fungus, Batrachochytrium dendrobatidis ("Bd"). We are studying the prevalence of Bd in natural populations of amphibians and how ecology and environmental conditions vary individual and population responses to the fungus.
B. Population & Community Ecology
We primarily work on tropical amphibian ecology at multiple upland sites in Latin America. Some sites have already experienced declines and we resurvey transects to determine changes in amphibian populations. Other sites have not experienced declines and at these sites we conduct various studies on these amphibians to establish differences in ecology between species predicted to survive and those predicted to decline. At each site we 1) determine the diversity and abundance of adult amphibians and reptiles, 2) collect ecological data (reproductive parameters, longevity, movements) for the more common species through mark-recapture studies, and 3) document the abundance, diversity, habitat preferences, density, growth and development of embryonic and larval stages of amphibians. Using these survey data we are building a species-specific database of habitat preference and abundance, and, for focal species, individual movement, gene flow, and fluctuating asymmetry. Several past graduate students have studied the demography, population biology, and ecology of particular species of frogs.
C. Ecosystem Ecology
Given the abundance and diversity of frogs and tadpoles at tropical sites, the dual role of amphibians in the food web (insectivorous adults and herbivorous tadpoles), and the bimodal life cycle (terrestrial adults and aquatic larvae) the loss of a large portion of the amphibian biomass might have big impacts on aquatic and terrestrial ecosystems. We are comparing tropical mountain stream foodwebs between healthy and decline sites, to determine the impact of amphibian declines on these ecosystems. We have done small-scale removal experiments, are in the process of establishing the spatio-temporal variation in tadpole assemblages, and are beginning to quantify the trophic links between frogs and predatory snakes. In a project very similar in concept to the tropical stream tadpole project is a local study on Illinois forest pond salamanders, especially how hydroperiod and species assemblage influence the amount of salamander reproduction, survival, and subsequent export into the forest.
SIUC Department of Zoology