Hybridization between lineages has immediate effects on ecological interactions among hybridizing species and their communities and related evolutionary processes (selection and gene flow). The expanded range of genetic and phenotypic variation that results from hybridization may alter the distribution of ecologically important traits in hybridizing species, thereby affecting environmental tolerances, species interactions, population regulation, and mechanisms of coexistence. Environmental variation also influences species distributions, the intensity and outcome of species interactions, and patterns of phenotypic and genetic variation over space and time. One of the central challenges to both basic ecology and applied species management is to understand the effects of interacting, potentially synergistic forces on the evolutionary and ecological dynamics of populations and communities. Here I examine the joint effects of environmental variation and hybridization between the endemic, threatened California Tiger Salamander (Ambystoma californiense) and introduced Barred Tiger Salamander (Ambystoma tigrinum mavortium) on the ecology of an assemblage of pond-breeding amphibians.
In Chapter one, I examine the impacts of spatial variation in pond structure (hydroperiod and vegetation structure) on California Tiger Salamander survival and interactions with California Newts (Taricha torosa) and Pacific Chorus Frogs (Pseudacris regilla). In Chapter two, I investigate the ecological consequences of tiger salamander hybridization, examining genetic differences in phenotype between California Tiger Salamanders and different classes of hybrids, the genetic basis of ecologically important phenotypes, and the effects of hybrid tiger salamanders on the survival and performance of larval California Tiger Salamanders, California Newts, and Pacific Chorus Frogs. In Chapter three, I look at the effects of landscape variation on endemic and hybrid larval fitness in the human-modified agricultural landscape of the Salinas Valley, California. In Chapter four, I investigate the potential for environmental variation to promote coexistence between Barred Tiger Salamanders (hybrid proxy) and California Newts.
|Advisor:||Shaffer, Howard B., Chesson, Peter L.|
|Commitee:||Fitzpatrick, Benjamin M., Lawler, Sharon P.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 72/05, Dissertation Abstracts International|
|Subjects:||Ecology, Evolution and Development|
|Keywords:||Ambystoma californiense, Amphibian, Coexistence, Environmental variation, Hybridization, Invasion, Taricha torosa|
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