Thesis (M.A.)--Humboldt State University, 2008. / Includes bibliographical references (leaves 72-79). Also available via Humboldt Digital Scholar.

The purpose of this study was to investigate the survival and movements of newly metamorphosed Northern Red-legged frogs (Rana aurora aurora) as they emigrated from two ephemeral breeding ponds. Quantifying survival and movement rates will be important to our understanding how changes to terrestrial and aquatic systems affect behavior and population dynamics. I manipulated food availability for a subset of uniquely marked metamorphic frogs and then analyzed temporal and spatial aspects of their recapture in forest pitfall traps relative to body size and date of metamorphosis. The probability of surviving and emigrating increased strongly with increasing body size and declined for frogs metamorphosing later in the season. Larger body size was associated with earlier emigration and greater correlation of movements with rainfall events. Within a pond, the time elapsed between metamorphosis and emigration was not affected by the pond drying. My results demonstrate that conditions during the tadpole stage which affect body size and the timing of metamorphosis may have a dramatic impact on the performance of frogs during their initial transition into the terrestrial environment. / Graduation date: 2004

The ontogeny of the enzyme LDH has been studied in two species of amphibians (Amblystoma gracile and Rana aurora) as it provides a sensitive gauge of the state of differentiation of the organism, since the number and proportions of LDH isozymes present exhibit temporal and species specificity, thereby reflecting the degree of activity of the controlling genes. The presence of LDH in all stages of both species examined was established by assaying embryo homogenates for LDH activity, and the LDH was resolved into isozymic patterns by the methods of starch gel and disc electrophoresis. Specific enzyme activity for each developmental stage was correlated with the morphological events then occurring and the isozyme patterns obtained were discussed in terms of showing an increase in complexity during ontogeny and in terms of the current LDH isozyme hypothesis. A modified hypothesis was advanced to account for some of the experimental findings. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 44-46). Also available via Humboldt Digital Scholar.

Thesis (M.S.)--California Polytechnic State University, 2010. / Title from PDF title page; viewed on March 18, 2010. Major professor: Royden Nakamura, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Biological Sciences." "February 2010." Includes bibliographical references (p. 78-90).

The conservation of aquatic-breeding amphibian populations and their habitats is increasingly challenged by urban and rural development, which is occurring more intensively and more rapidly than ever before. Some species are now impacted by development throughout their range. This has forced a re-evaluation of the potential of developed landscapes for providing habitat and contributing to regional conservation strategies. For many amphibians, little is known about the criteria necessary for persistence in a developed landscape. Considerable variation in the physiology, habitat requirements, and movement behaviour of amphibians suggests that responses to habitat loss, alteration, and fragmentation are species-specific. In this thesis, I investigate species-habitat relationships for the northern red-legged frog (Rana aurora) and the Pacific chorus frog (Pseudacris regilla) in a mixed urban-rural landscape in southwestern British Columbia to evaluate the potential for species persistence despite urban and rural development throughout their range. I used repeat auditory surveys of the species’ breeding chorus to determine presence or absence at potential breeding wetlands. I then related species occurrence and abundance to characteristics of the aquatic and terrestrial environment measured at multiple spatial scales. Both species were found to use rural and urban wetlands, though R. aurora were rarely detected while P. regilla were common. Occurrence was best explained by characteristics of the terrestrial environment, rather than within-wetland characteristics, though influential terrestrial characteristics and their scale of impact differed between species. Within the context of the developed landscape, I identify species-specific positive and negative habitat associations and suggest the spatial scales at which management of these habitat characteristics will be most effective. These criteria may help to explain the species’ current distribution, prioritize management strategies, predict the effectiveness of habitat conservation and restoration projects, and inform development in municipalities seeking to maintain or enhance amphibian diversity. / Graduate / 2019-09-11

Alien fish have been implicated in the decline of Rana draytonii (California red-legged frog) and Pseudacris regilla (Pacific treefrog) populations. Micropterus salmoides (largemouth bass) is a common sport fish that has been introduced into the sympatric range of these two anuran species; however, no studies have investigated the individual influence that this alien fish has on these two species. I conducted M. salmoides control or eradication experiments during a four year study in two ponds within the Transverse Mountain Range of Santa Barbara County, California. Changes in the densities of all life stages of R. draytonii and P. regilla were assessed through repeated visual encounter surveys. In response to the manipulations of the M. salmoides populations there was an increase in the density of both species. For R. draytonii, this salient increase in density was recorded in the larval and metamorph life stages. For P. regilla, a slight, yet steady increase in the density of adult, metamorph, and larval life stages was recorded. My results suggest that M. salmoides can be controlled or eradicated from lentic waterbodies and provides reasonable evidence that the negative effects of this species on R. draytonii and P. regilla populations can be minimized or reversed. The reversal of these effects may translate into increases in the densities and potential recruitment of these two native anurans. Therefore, my results provide tentative support that the control or eradication of M. salmoides where they cohabitate with these two species may be a viable conservation measure for R. draytonii and P. regilla populations. Since my study was performed at a very local scale and all results are strictly observational and descriptive, additional studies should be performed at a larger spatial scale and buttressed with controlled laboratory and field enclosures experiments to identify the causal factors responsible for the identified patterns.