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I investigated the value of under-road tunnels as a conservation strategy to protect a long-toed salamander population, in south-west Alberta, whose overwintering sites and breeding habitat (Linnet Lake) are separated by a road. I conducted a mark-recapture study from 2008-2009, capturing salamanders using roadside fences and pitfall traps. Four tunnels were monitored in 2009 using traps and cameras. A 2008 estimate indicated that the population declined by 60% since 1994, however, road mortality was dramatically reduced following installation of fences and tunnels. Camera and trap data documented 130 salamanders navigating tunnels in 2009. I found little evidence of juvenile recruitment from Linnet Lake, likely because of predation by lake chub. Experiments showed that lake chub consumed salamander larvae, and fish presence altered larval behaviour. Continued monitoring is needed to determine if reduced road mortality translates into population gains, and whether fish predation threatens the persistence of the long-toed salamander population. / Ecology

Cannibalism is a seemingly aberrant interaction, appearing counter to the fitness of individuals. Yet cannibalism is not overly uncommon, and naturally occurs among aquatic organisms, including larval amphibians. In temporary wetlands larval amphibians are in a race to complete metamorphosis before their aquatic habitat disappears. When intraspecific competition intensifies, eating conspecifics may represent a beneficial if not necessary strategy. The research presented within this thesis aims to characterize factors that influence cannibalism within populations of larval amphibians. Wood frog tadpoles (Lithobates sylvaticus) were used to test potential benefits of cannibalism as a diet, determine if dietary quality and nutritional stress influence cannibalism, and investigate the roles of competition and chemical cues in influencing cannibalism. Larval long-toed salamanders (Ambystoma macrodactylum), and ringed salamanders (A. annulatum) were used to investigate a functional link between trophic polymorphism and cannibalism in natural populations. Results suggest that perceived increases in competition may stimulate some individuals to become less risk averse, and more aggressive, which may in turn facilitate cannibalistic behaviour. Cannibalism itself provided only conditional benefits to larval wood frogs, rather than the optimal growth that would be expected from an ideal diet. However, this may have been the result of individual variation in response to the diet and/or conspecific cues as opposed to a nutritional deficit. In conditions where tadpoles could perceive increased competition they altered their behaviour and morphology in ways that may improve their foraging success and potentially promote cannibalism. Finally, a functional link appears to exist between head morphology and cannibalism in natural wetlands. However, the appearance of this morphology appears related to conditions that may facilitate increased population densities through rapid pond drying.

Global amphibian declines have been attributed to numerous and often synergistic causes, such as invasive species, pathogens, and ultraviolet-B (UV-B) radiation. The effects of these stressors are context dependent and can vary with location, species, and populations. As sensitivity to UV-B has shown inconsistencies across amphibian taxa, it can be expected that variation also occurs between populations of a single species. High elevation populations of the long-toed salamander (Ambystoma macrodactylum) face exponentially higher UV-B radiation levels relative to low elevation populations and these levels are predicted to increase in conjunction with continued ozone depletion. We hypothesized that breeding long-toed salamander females at high elevations have modified oviposition behavior to better protect embryos from UV-B induced damage. In addition, we hypothesized that long-toed salamander embryos at high elevation would exhibit elevated photolyase activity, a photo-reactivating enzyme that repairs UV-B radiation-induced damage to DNA. We predicted that this behavioral defense strategy would be employed together with an elevated physiological response as a correlated defense response to increased levels of UV-B radiation in high elevation populations. We surveyed high and low elevation long-toed salamander breeding sites throughout Oregon to quantify oviposition site characteristics and associated UV-B profiles. We simultaneously collected embryos for quantification of photolyase activity in a bacterial transformation assay. We found significant differences in oviposition behavior across elevations, with high elevation breeding females ovipositing in deeper water and using UV-B protective refugia. Oviposition sites at low elevations, however, were most often found in UV-B exposed microhabitats located at the surface of the water. This population difference in oviposition behavior resulted in a standardization of UV-B and temperature conditions for long-toed salamander embryos across elevation. In contrast, we found no population differentiation in photolyase activity between high and low elevation breeding sites. This indicates that behavioral selection for UV-B protected oviposition substrates may either be negating the need for increased photolyase activity in long-toed salamander embryos, or that populations lack the capacity to adapt a heightened physiological response to UV-B at high elevations. Together, these results show how trade-offs in physiology and behavior are a unique adaptation to a significant environmental stressor. Further research into the susceptibility of amphibian species to changing environmental conditions may help to demonstrate the effectiveness of correlated trait responses and plasticity in behavior, and species persistence under changing climate regimes. / Graduation date: 2012