Animals can be naturally exposed simultaneously to multiple stressors. These include habitat changes, contaminants, diseases, invasive species, parasitism, and predation. Exposure to various combinations of biotic and abiotic stressors may induce behavioral changes that affect the way an individual interacts within its environment.Like other groups of organisms, amphibians are exposed...
Climate change is predicted to affect ecosystems, including systems already stressed by human impacts. One ecosystem that is already highly impacted by human land use is the cold headwater stream system of the Pacific Northwest. One method of assessing the function of an ecosystem is by using an indicator species....
Due to past hiring practices U.S. federal agencies have workforces that do not match the diversity of the populations they serve. In 2011, the Partnership for Public Service found that the United States Forest Service (USFS) ranked number 149 out of 206 agencies in the category of ‘Support for Diversity,’...
Relations between the diversity of juvenile anadromous salmonids and pool features
were examined in a managed and a pristine watershed in Oregon during the summer of
1990. There were no differences (p>0.05) in pool depth, velocity or pool wood volumes
between streams. However, the pristine system had twice the number...
My dissertation focuses on the factors that influence variation in female reproductive success in plethodontid salamanders and in toads. Variation in reproductive success fuels evolutionary change. Although, females often have been overlooked in studies of reproductive success due to perceived lower levels of variation when compared to variation in male...
An investigation of the genetic and meristic patterns of coastal cutthroat trout (Oncorhynchus clarki clarki) in two coastal basins, one in Oregon and one in Alaska, revealed varying degrees of differences among populations within each site. Coastal cutthroat trout collected from seven sites above and below barriers from Elk River,...
A major goal of conservation biology is to elucidate the population genetic structure in threatened species and assess the relative importance of the evolutionary forces that shape that population genetic structure. I conducted three studies in the declining amphibian Rana cascadae to assess levels of population genetic differentiation and the...
According to general top-down trophic theory, in the presence of carnivores, herbivore behavior and/or densities could change and result in an overall decrease in herbivory on plant communities. In this dissertation, I examined the potential relationship between gray wolf (Canis lupus) presence and absence on elk (Cervus elaphus) herbivory of...