Ecological Mechanisms That Enhance Community Stability, And Their Consequences For The Conservation Of An Endangered California Salamander

EPA Grant Number: F5E11030
Title: Ecological Mechanisms That Enhance Community Stability, And Their Consequences For The Conservation Of An Endangered California Salamander
Investigators: Ryan, Maureen E.
Institution: University of California - Davis
EPA Project Officer: Klieforth, Barbara I
Project Period: September 1, 2005 through August 31, 2008
Project Amount: $109,955
RFA: STAR Graduate Fellowships (2005) RFA Text |  Recipients Lists
Research Category: Academic Fellowships


My research addresses four primary questions:

  1. Does environmental variation promote coexistence between the California tiger salamander, Ambystoma californiense, and the California newt, Taricha torosa?
  2. How do dispersal and habitat selection interact with local community dynamics to influence species diversity in this community on a regional scale?
  3. Can anthropogenic changes in habitat features shift the balance of species interactions in favor of Taricha torosa by influencing the strength of coexistence mechanisms?
  4. In what specific ways can conservation and management of Ambystoma californiense be improved by understanding their interactions and the nature of coexistence mechanisms operating in their community?


My research focuses on interactions between the endangered California tiger salamander (Ambystoma californiense) and the California newt (Taricha torosa), the role of environmental variability in promoting coexistence between these species, and the effects of anthropogenic manipulation of shared breeding habitat on their community dynamics. The majority of habitat occupied by Ambystoma californiense is in some way influenced by anthropogenic manipulation (primarily through pond manipulation and impediments to dispersal). Habitat characteristics such as pond depth, pond permanence and vegetative complexity, all subject to change with pond manipulation, may influence presence and recruitment success of California tiger salamanders by affecting community composition, levels of predation and competitive ability. The distribution of types of breeding habitats and the ability of each species to disperse between them is therefore expected to influence regional community dynamics. Using a combination of theoretical models, mesocosm experiments and field surveys, I am examining how specific mechanisms that act through environmental variation (the storage effect and growth-density covariance) promote species diversity in this community and how these mechanisms are affected by anthropogenic manipulation, with the goal of identifying specific ways in which conservation methods for the CA tiger salamander could be improved.

Expected Results:

From a theoretical perspective, I expect that this research will contribute to our understanding of how the storage effect promotes diversity in vertebrate amphibian communities. From a conservation perspective, understanding the mechanisms that allow for coexistence between Ambystoma californiense and Taricha torosa will provide a means through which to better manage the California tiger salamander across the remainder of its range.

Supplemental Keywords:

amphibian, California tiger salamander, Ambystoma californiense, California newt, Taricha torosa, salamander interactions, community ecology, conservation, intraguild predation, competition, storage effect, growth-density covariance, environmental variation, environmental heterogeneity, coexistence, landscape ecology, ecological theory, amphibian declines, diversity maintenance, dispersal, mesocosm, endangered species, anthropogenic effects, habitat structure,, Scientific Discipline, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, Habitat, Species, Ecology and Ecosystems, Biology, endangered species, habitat selection, community composition, habitat disturbance, anthropogenic stressors, conservation biology, California salamander

Progress and Final Reports:

  • 2006
  • 2007
  • Final