Ecological consequences of water loss under climate change in small ectotherms

Eric Alexander Riddell, Clemson University


Warming climates threaten to reduce biodiversity across the planet, yet the capacity of organisms to minimize the effects of climate change are rarely considered in current ecological predictions of climate change. Organisms can minimize the effect of warming through behavioral, physiological, and morphological processes that limit exposure to lethal conditions or improve performance. Therefore, integrating these mechanisms into ecological models might improve predictions on the loss of biodiversity under climate change. For my dissertation, I focus on the physiological processes that influence habitat suitability in a group of terrestrial, lungless salamanders (Plethodon spp.) found in the core of the global hotspot of salamander diversity. These salamanders may suffer from the risk of dehydration due to their high rates of water loss and the potential rise in evaporation rates under climate change. Therefore, I focused on the ecological consequences of skin resistance to water loss, the most physiologically-informative metric of water loss. I used a combination of physiological experiments and species distribution modeling to demonstrate that skin resistance to water loss might limit the spatial distribution of these species. Laboratory experiments uncovered plasticity of skin resistance to water loss that could potentially buffer salamanders from the consequences of warming. However, ecological predictions from species distribution models indicate that physiological and behavioral plasticity were insufficient strategies to avoid extinction under climate change. Upon modeling historic climate change, plasticity in seasonal activity and dispersal capacities represent critical strategies that might have promoted persistence during extreme climatic oscillations at the end of the Pleistocene epoch. Further experiments demonstrated that the ecological benefits of limiting water loss might be determined by trade-offs between skin resistance to water loss and metabolism. These results demonstrate that incorporating physiological mechanism represent an important component of predicting ecological dynamics.