Meeting Abstract
The intertidal zone is a dynamic environment where species zonate as a consequence of their relative tolerances to abiotic stress. In order to assess stress responsiveness among intertidal species, we utilized comparative next-generation sequencing to investigate the transcriptomic responses of two, differentially sensitive, intertidal species of porcelain crab (genus Petrolisthes) to natural variability in temperature and pH. Congeners were exposed to either a low-variability, ambient control or a high-variability stress treatment where temperature and pH were spiked, mimicking natural diel fluctuations. Gill tissue was collected from crabs exposed to a single temperature/pH cycle (naïve response) and from those exposed to several cycles over two-weeks (acclimated response). Genes strongly diferentially expressed included those involved in acid-base regulation (VHAs) and stress recovery (HSPs), and patterns of expression differed significantly between species in ecologically relevant ways. Although P. manimaculcus exhibited a greater degree of expression change, nearly five times more genes were differentially expressed in P. cinctipes. In addition, for P. manimaculus, expression changes at a given exposure did not differ significantly between stress and ambient treatments whereas both naïve and acclimated individuals of P. cinctipes showed strong, stress-specific alteration in expression of acid-base regulatory genes. These results suggest that P. manimaculus’ sensitivity to abiotic stress may be a result of a reduced stress response generally, and a limited capacity to alter expression of acid-base regulatory proteins in particular. This reduced responsiveness may be a consistent feature among species susceptible to environmental stress, setting modern habitat limits and potentially acting as a primary determinant of winners and losers under future climate change.
