Amphibians under stress: life history, density dependence, and differences in vulnerability

Numerous anthropogenic stressors are known drivers of amphibian declines. Nonetheless, research has revealed few lessons for preventing declines in advance of their occurrence. This thesis presents a conceptual framework for identifying when spatial and temporal overlap of density-dependent bottlenecks, life-history traits, and stressors increase decline risk. I evaluated this framework using published empirical amphibian density-dependence data, and found that population dynamics and life-history theory could be useful in prioritizing vulnerability to stressors, though current data deficiencies limit evidence of correlations between these factors. In an experimental test with three frog species, I found that not all species share the same sensitivities to combined climate warming and habitat permanency scenarios. These results suggest larval life-history requirements can influence species’ responses to climate change. Integrating theoretical and empirical tests provides useful tools for estimating species vulnerability and helps identify gaps in our knowledge of the dynamics that govern amphibian responses to stressors.