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Date of Graduation
Master of Science (MS)
Department of Biology
Future emissions scenarios project climate change to increase average global temperatures by at least two ℃ in the next 50 years resulting in changes in local climate and causing increased variability within microclimates. Ectotherms are especially sensitive to climate change due to their dependence on environmental temperatures to regulate physiological functions. Changes in temperature are likely to impact thermally cued processes within amphibians and result in changes in variable magnitudes and directions within local populations.
Salamanders were placed in cups and partially submerged in a water bath and heated at a rate of ~0.27℃/ minute. Once salamanders were unable to right themselves after 5 seconds their CTmax was determined.
Analysis of CTmax by morph resulted in no statistically significant difference between morph CTmax. There was no apparent statistically significant difference in the CTmax values between sexes within or across morphs. There were statistically significant differences detected across salamander age class. Hatchling salamanders CTmax values were 11℃ lower than adult paedomorphic salamanders while larval salamander CTmax values were 9.4℃ lower than adult paedomorphic salamanders. Metamorphic salamander CTmax were not statistically significant along an elevational gradient CTmax values were similar amongst high and low elevation sites. Locally in the low elevation sites, metamorphic salamander CTmax were statistically significant different from year to year. Metamorphs and paedomorphs reported statistically significant differences in body temperatures in several months throughout the year. Environmental conditions in the aquatic and terrestrial environments showed remarkably similar temperatures throughout the year with slight differences in windows of opportunities within morphs. Light intensity showed ponds begin to thaw out in early may resulting in earlier activity in paedomorphic salamanders. Aquatic salamanders likely have availability to resources sooner than terrestrial salamanders that must wait on snowmelt to cue them to emerge from their burrows. During the currently defined active season, I determined differences in warming tolerance between morphs with metamorphic salamanders showing higher warming tolerances than paedomorphic salamanders.
My research provides greater insight into thermal physiology of alpine adapted ectothermic organisms and is among the first of its kind to incorporate true body temperature of salamanders that can be directly correlated to critical thermal maxima. This research also combines physiological and environmental approaches to determine a thermal profile for various morphs, sexes, and age class of alpine salamanders. Future research should go beyond collecting CTmax of salamanders and collect CTmin data to provide a complete estimate of thermal breadth of animals in these alpine environments to provide a complete picture of their context dependent responses to climate change.
Richardson, Kentrell, "Understanding context dependent responses to climate change in Arizona Tiger Salamanders (Ambystoma mavortium nebulosum)" (2023). Masters Theses, 2020-current. 218.
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