Meeting Abstract
Stress responses allow organisms to cope with environmental changes by allocating resources toward processes that enhance survival. Over short timescales, stress may increases survivorship in adverse conditions, but stress becomes detrimental over longer periods. At species range limits, where physical barriers are not limiting, individuals may be constrained by their physiology. Here, individuals are more likely to encounter physiologically demanding conditions that will worsen if the climate warms. Suitable habitat for Plethodontid salamanders in the southern Appalachians is predicted to decrease by up to 40% as early as 2020. Given these salamanders’ reliance on cool and moist habitats, our understanding of their responses to such change will depend on: (1) how physiological stresses vary with the natural hydrothermal gradients of elevation and latitude, (2) whether current stress levels help to predict future species range limits. We assessed stress using leukocyte ratios (neutrophils:lymphocytes) from field-fresh southern grey-cheeked salamanders (Plethodon metcalfi) to compare relative background stress levels between collection sites. Individuals were sampled across the known species limits from as wide a range of elevation as possible to encompass environmental variation. Stress levels are expected to increase with decreased elevation and latitude. Therefore, as the climate warms, individuals at low and southern sites will face greater physiological demands and likelihood of local extinction. Future work will test a prior background stress predictions based on environmental and locality data, and tease apart the timescale at which stressors act to examine factors that may impact range shifts.
