Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 118-131).

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references. Also available on the World Wide Web.

The red-backed salamander (RBS; Plethodon cinereus) has a large geographic range and, though it is common throughout, abundance varies spatially. It has been studied extensively for at least a century and as a result; its distribution, habitat use, behavioral ecology, reproductive ecology, and ecological role are well understood in comparison to other cryptic wildlife. Multiple sampling methods have been developed to monitor RBS, and I discuss in detail one common method – artificial cover objects (ACOs). Spatial capture-recapture (SCR) is uniquely suited to estimate population parameters, including true density, and is paired well with spatially referenced sampling methods, such as ACOs, and animals capable of retaining unique marks, such as RBS. In the introduction of this thesis, I review RBS, ACOs, and SCR independently in detail, and go on to discuss their compatibility for monitoring terrestrial salamander populations. Detailed, and often range-wide, monitoring of ecosystems is necessary to gather the information needed to achieve broad multiple-scale conservation objectives. Indicator species are recommended tools for filling in gaps of knowledge where these range-wide data do not exist. The use of indicator species is precluded by the lack of evaluation of candidate indicators and their relationship to indicated processes. In this thesis, I discuss in detail the practicality of indicator species as wildlife management tools, and challenges in their application – primarily their practicality when direct measurement of a variable of interest is possible. I advocate for integrative indicator species applications that make use of relationships to latent variables, review two conceptual models involving latent variables, and propose a modification to these models that makes relationships between variables more explicit. Inference of among-population variation to adaptive capacity, response to large-scale threats, and the condition of ecosystems is limited in part by unstandardized methods. Ecological relationships are made difficult to characterize by gaps in data - and this is especially true of links between indicator species their and related ecosystem processes. Using a candidate indicator species, I tested the congruence of population parameter estimates from study designs that varied. In Wendell State Forest, MA, I manipulated spatial arrangements of artificial cover objects (ACO) arrays and evaluated their use for monitoring terrestrial salamanders. ACOs mimic natural habitat - and attraction of RBS to traps may induce behavioral bias in parameter estimates if not accounted for. I sought to determine if variation in ACO design can be accommodated to make comparable estimates. I found that analyzing data from ACOs using spatial capture-recapture (SCR) modeling produces consistent within-population density estimates regardless of ACO configuration.

In terrestrial habitats with a history of mining activity and previous or ongoing reclamation efforts, understanding the effects of acidification on the ecology of amphibians is an important part of the restoration process and the conservation of local amphibian populations. Pond-breeding amphibians spend much of their post metamorphic life history in direct contact with the soil in upland habitat adjacent to aquatic breeding sites. I reared recently metamorphosed marbled salamanders (Ambystoma opacum) to evaluate the role of soil acidity on determinants of fitness such as growth and survival. My results indicate that a substrate of pH 4 was lethal to recent A. opacum metamorphs. Among animals surviving the higher pH treatments, we found that individuals reared on a pH 5 substrate suffered a reduction in total length and snout vent length by the end of the experiment. The mechanisms of acidity are complex; both hydrogen ions and anions contribute to negative effects on amphibians. Sulfuric acid has larger negative effects than other acids and sulfates can cause reductions in growth without a change in pH. I reared larval spotted (Ambystoma maculatum) and Jefferson salamanders (Ambystoma jeffersonianum) to evaluate the effects of pH and sulfates on two species with differential acid resistances. My results indicate that a pH of 4 is lethal to larval salamanders of both species. In high sulfate treatments there was an early reduction in growth in the spotted salamander, but not in the Jefferson salamander showing that acid resistance applies to the effects of sulfates as well as hydrogen ions. Together, our results suggest that acid and sulfate deposition can affect the fitness of Ambystoma salamanders through direct mortality and a decrease the growth rate of salamanders both as larvae and subsequent to metamorphosis.

North American Giant Salamanders (Cryptobranchus alleganiensis), commonly known as hellbenders, have been experiencing a population decline for decades due to human influences, such as pollution and habitat destruction. Many efforts are underway to save the hellbender but their entire potential geographical range has not been well-studied. Currently, hellbender populations are delineated by county boundaries and are on the International Union for Conservation of Nature Red List. The Genetic Algorithm for Rule-set Production, an Ecological Niche Model, was used to model the current hellbender potential distribution at a macro-scale under two different environmental scenarios. Additionally, future potential distributions were projected under two different climate change scenarios (Representative Concentration Pathways) to predict where possible habitat loss and expansion may occur in coming decades. Niche modeling was also used to evaluate the influence of environmental parameters across geography and between two sub-species of hellbender, the Eastern hellbender and the Ozark hellbender. Results showed that vegetation indices had some influence on current distribution predictions, while future models revealed that potentially large areas of currently suitable habitat may be lost, especially in the Ozark Mountains and the Southern Appalachian Mountains. Habitat expansion was predicted for several areas in the New England region of the northern Appalachian Mountains. The most influential variables were the maximum temperature of the warmest month, temperature annual range, and annual precipitation, while slope and elevation were less influential. However, areas of very high slope and elevation were not suitable for hellbenders, confirming previous descriptive habitat analyses. Current and future modeled distributions will provide conservationists with a more specific, and quantified, geographical and ecological description of where environmentally suitable areas exist for hellbenders. Micro-scale, stream-based studies provide areas of future research.

abstract: Emerging infectious diseases (EIDs) in vulnerable populations are a proposed cause of reduced global biodiversity due to local and regional extinctions. Chytridiomycosis, a fungal disease caused by Batrachochytrium dendrobatidis (Bd), is affecting amphibian populations worldwide. Chapter 1 of this thesis reports using lab-raised larval tiger salamanders (Ambystoma tigrinum nebulosum), collected as eggs, to test if Bd infects them. Bd infects metamorphosed tiger salamanders; however, it is currently unknown if larvae can be infected by Bd. Adult frogs tend to host Bd on ventral surfaces and hind legs while tadpoles host Bd in keratinized mouthparts. No research has considered differences in infection between life stages of salamanders. It was hypothesized that Bd can colonize larvae in the same manner as metamorphosed animals. Larval salamanders were inoculated to test if Bd concentrations differ among body regions in larvae compared to metamorphosed salamanders. Larvae can carry Bd with the concentration of Bd varying between body region. Chapter 2 report using native tiger salamanders (Ambystoma tigrinum nebulosum), from northern Arizona and Bd as a study system to test if Bd is native or introduced to Arizona. It was hypothesized that Bd is not endemic to Arizona, but is introduced. There are multiple hypotheses regarding potential routes Bd may have traveled through Arizona and into Mexico. These hypotheses were tested using the Kaibab Plateau in Coconino County, Arizona, as a study site. The plateau is isolated from surrounding areas by the Grand Canyon to the south and the Vermillion Cliffs to the north serving as major biogeographical barriers. It is hypothesized that tiger salamanders are not dispersing into or out of the Kaibab Plateau due to geological restrictions. Bd, therefore, should not be present on salamanders on the Kaibab Plateau due to geological restriction. Tiger salamanders in stock tanks located on the Kaibab as well as preserved museum specimens housed in the Arizona State University Natural History Collection were sampled. The results indicate that Bd occurs at low levels on Kaibab Plateau tiger salamanders. / Dissertation/Thesis / Masters Thesis Biology 2019

The genetics of colonization is understudied in salamanders but has large conservation implications as new habitats are formed or restored to their previous condition. The 1980 eruption of Mount St. Helens provided a natural experiment to study the genetic effects of a large infrequent environmental disturbance on two species of salamander, Taricha granulosa (Rough-skinned newt) and Ambystoma gracile (Northwestern salamander). Both these species breed in ponds, and are thought to exhibit high breeding site fidelity and low vagility. I designated three treatments based on the effects of the eruption: new ponds (created by the eruption, immigrants only), recovery lakes (in blast zone, survivors plus immigrants), and reference lakes (unaffected by eruption, assumed to represent pre-eruption genetic diversity measures). Salamanders took at least nine years to colonize the new ponds. I studied the population genetics of colonization and recovery using microsatellites and AFLPs (amplified fragment length polymorphisms) to measure genetic diversity, gene flow, and population substructure at Mount St. Helens National Volcanic Monument. Based on population genetics theory and the life history characteristics of these pond-breeding amphibians, I predicted that genetic diversity would be lower in newly colonized ponds compared to recovery or reference sites. I also expected significant levels of population substructuring. Finally, I predicted that because of their lower vagility and large number of neotenes, that A. gracile would have less gene flow and a greater degree of population substructuring than T. granulosa. My predictions were not supported by my data. There was no loss of genetic diversity in new or recovery populations in either species. There was no strong evidence for population substructure by either AMOVA, isolation by distance or principal components analysis. Gene flow (Fst) was high in both species. Taricha granulosa and A. gracile were found to be resistant to a large infrequent environmental disturbance. Loss of genetic variability in new populations cannot automatically be assumed. Predicting dispersal and colonization ability based on the broad category of pond-breeding amphibian is not always reliable.

No description available.

Thesis (Ph. D.)--North Carolina State University, 2002. / Title from PDF t.p. (viewed on Aug. 21, 2004). Includes vita. Includes bibliographical references.

Thesis (M.S.)--Marshall University, 2002. / Title from document title page. Document formatted into pages; contains vi, 81 p. including illustrations. Includes bibliographical references (p. 41-44).