Meeting Abstract

P1.67  Saturday, Jan. 4 15:30  Environmental variation and the evolution of immune function in wolf spiders SHAIKH, H*; STEFFENSON, M; MANN, W; BEACH, J; MYDLARZ, L; University of Texas, Arlington; University of Texas, Arlington; University of Texas, Arlington; University of Texas, Arlington; University of Texas, Arlington humera.shaikh@mavs.uta.edu

Temperatures are expected to rise with climate change, with drier, hotter summers expected in subtropical regions. It is important to understand how species will respond to increased temperatures, especially in arthropods, as they cannot regulate their own body temperature. As a result, ectotherms must allocate a higher proportion of energy toward managing temperature stress than endotherms. The goal of this study was to identify whether changing environmental conditions (e.g. temperature) over the course of the growing season influences basal immunity among wolf spiders (Tigrosa helluo) in North Texas. Sixteen male T. helluo were collected every two weeks from May to November. Spiders were brought back to the laboratory and had their running speed recorded by chasing them down a track with a wooden dowel. The following day, spiders were weighed and hemolymph was extracted, homogenized, and frozen for immunological assessment (protein concentration, antioxidant and antimicrobial activity). Carapace length of each specimen using digital microscopy was also recorded. Preliminary results indicate that body mass, running speed, and carapace length did not significantly change over the growing season. However, protein concentration and immune response activity significantly increased from late spring to mid-summer. As temperatures increased through mid-summer, the number of prey items may have as well, resulting in an increase in protein concentrations. This in turn could increase the amount of energy individuals had to invest in a temperature stress response, thus also increasing constitutive immune activity. However, spiders may not have had enough energy to invest in all physiological responses and thus trade-offs between running speed and immune response are expected.