The relationship between sexual selection and immune function in a wolf spider (#66)
Ground-active wolf spiders must combat constant exposure to soil-dwelling parasites and pathogens, as well as the potential for exposure from food and water sources. As a consequence, these spiders have developed an effective innate immune system. In this study, we evaluate the relationship between immune function and multimodal sexual signaling in a terrestrial wolf spider species, Schizocosa ocreata. This species has energetically costly multimodal courtship, which has been shown previously to be negatively impacted by bacterial infection as a juvenile. We found that males who had been previously exposed to a bacterial pathogen Pseudomonas aeruginosa in the laboratory as juveniles had significantly higher adult immune function than those who had not been previously exposed to a pathogen. In addition, adult tuft size (secondary sexual character) was significantly correlated with adult immune function within males who had not previously been exposed to a pathogen. We also found that energetically costly courtship behavior significantly reduced male immune response, and that males with relatively larger tufts are better able to sustain an immune response after courtship. Lastly, we found that infection as a juvenile significantly reduced courtship behavior and mating success, but that infection as an adult has the potential to increase courtship and mating success. This supports the assumption that secondary sex characters enforce signal honesty by being good indicators of overall male health.