Meeting Abstract
It remains unclear how strategies used by salamanders to maintain thermal and hydric balance vary in response to one another, and whether this relationship varies geographically. Behaviorally, salamanders cease activity once they dehydrate to a certain threshold (the water limit threshold). Likewise, they will cease activity when they perceive themselves as becoming too warm (the voluntary thermal maxima). The cessation of activity prevents lethal levels of dehydration or heat stress, but also limits potential activity. Salamanders in warmer environments compensate by increasing cutaneous resistance to water loss to remain active. In this study, we will characterize the relationship between thermal limits and water loss using Plethodon metcalfi collected along an elevational gradient. We will first address how dehydration stress affects thermal maxima by measuring the voluntary and critical thermal maxima of salamanders at various hydration states. Additionally, we will measure resistance to water loss to test whether thermal limits vary in relation to water tightness. We will then place salamanders into two different acclimation treatments—a warm and dry treatment versus a cool and wet one. Measurements on acclimated animals will allow us to assess the plasticity of these traits, and whether acclimation alters the relationship between them. A better understanding of how salamanders balance thermal and hydric stress may further elucidate the capacity of this group to survive in a warming climate.
