Meeting Abstract
Global climate change may compress the amount of suitable thermal habitat for an organism in present distribution ranges. As a result, species distributions may shift causing novel species interactions. Behavioral interactions between predator and prey species can cause physiological stress; but whether competing for space causes physiological stress is unknown. Based on present temperatures and thermal performance, warming will likely cause Petrolisthes cinctipes to shift its distribution from the upper intertidal zone to the lower intertidal zone habitat of Petrolisthes manimaculis. Therefore, increased interactions are expected to occur between the porcelain crabs P. cinctipes and P. manimaculis. We hypothesized that crabs are more interactive in interspecific assemblages and that interactivity increases expression of cellular stress response genes. Interactions were observed in single and mixed species assemblages. Physiological stress was measured by the differential expression of six biomarkers for the cellular stress response (CSR). Crabs were more interactive in interspecific assemblages, but there was no relationship between interaction frequency and CSR. Contrary to our expectations, 100% of crabs in conspecific groups showed increased CSR as compared to 20-40% of crabs in interspecific groups. Interspecific competition for space may not induce the CSR in either species. Other physiological indicators, such as long-term injury and reproductive output, may better predict the indirect consequences of climate change on interspecific interactions and organismal stress.
