Research Interests

Amphibian Population Declines:

Since the early 1990s, we have been involved in assessing the significance of declining amphibian populations.  We have investigated this problem from several angles.  We are monitoring populations on a long-term basis. We are investigating specific causes for the declines and we are synthesizing data from various projects.  Specifically, we have looked at invasive species and their effects on amphibians, the spread of diseases, the role of environmental contamination and the effects of ultraviolet (UV) radiation.  We are also concerned with how various agents may interact with one another to affect amphibian populations.

WE DO NOT BELIEVE THAT THERE IS ONE SINGLE CAUSE FOR AMPHIBIAN POPULATION DECLINES.  In fact, it is obvious that there are many factors that contribute to amphibian population declines.  This depends upon the species, the region and the environmental conditions, among other things.  For a further discussion on how our laboratory views the complex nature of amphibian populations and declines, please click these links:  Click here for a recent overall review of the effects of UV-B on aquatic organisms.

We take several approaches to investigate amphibian population declines and extinctions. These include taking observations in the field and using laboratory, field and mesocosm experiments.

Steph Gervasi and a western toad and her favorite song...

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Host-Pathogen Biology:

Host-pathogen systems are ideal for answering many key questions in ecology and evolutionary biology and I have conducted several research projects in this area.  Host-pathogen systems have been part of my research program since I was a graduate student, and they are an important study area to me and my students today.  Papers I wrote in the 1980s represent some of my early conceptual/theoretical work on host-parasite and species diversity relationships.  I have also conducted more empirical studies on host-pathogen systems.  Several of my doctoral students have worked on host-pathogen relationships from ecological perspectives.  These students have investigated the effects of parasites on host behavior, how parasites regulate populations of small mammals, and the effects of pathogens on amphibian populations. As part of this research, we have been investigating the role of flatworms in causing amphibian limb deformities.   Recent papers co-authored with Pieter Johnson ( University of Colorado) reflect our views on the role of parasites in causing amphibian deformities. We have done a great deal of work on the pathogenic oomycete, Saprolegnia. Several of my graduate students have conducted portions of their thesis research on this pathogen.

We are heavily involved in studying the effects of the newly emerging infectious fungus, Batrachochytrium, on amphibians. Along with colleagues from several universities, we have been studying the effects of this fungus on larval and newly metamorphosed amphibians of various species. We are also investigating how this fungus may interact with other environmental variables such as UV-B radiation, contaminants and other environmental agents.

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Behavior:

Our laboratory has always been involved in studies of animal behavior. Although our primary subjects of our behavior studies are amphibians, we have also conducted studies involving small mammals and invertebrates.  We are interested in social behavior, reproductive behavior, and the evolution of behavior and many of the publications from our lab reflect those interests.

We have also investigated various aspects of amphibian chemical ecology and how behavior relates to Conservation Biology and Disease Ecology. These areas of behavior are of prime interest to members of my laboratory.

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Although most of our work is done in the Pacific Northwest, some of our work is done in the tropics.

An encounter with an iguana in Costa Rica

Crocodiles in Costa Rica

Bushmaster in Costa Rica