The interaction between physiology and behavior underlying complex life histories

Abstract

Abstract The pace-of-life syndrome hypothesis predicts that consistent variation in behavior should be linked to variation across individuals in physiological and other life history traits. Here, we examined the interaction between physiology and behavior in the Cambarid northern crayfish (Faxonius virilis) from its invaded range. The morphology of adult male Cambarid crayfish is accompanied by seasonal changes in sexual activity, a process called form alternation or cyclic dimorphism. Crayfish exhibit the reproductive form in the breeding season and subsequently molt into the non-reproductive form. Upon return of the breeding season, non-reproductive males molt back to their reproductive form. We repeatedly measured metabolic rate, body condition, and propensity to take risks in reproductive and non-reproductive northern crayfish. Higher risk-taking behavior was linked to a higher body condition consistent with the pace-of-life syndrome hypothesis. Individual differences in risk-taking behavior were only mildly repeatable. Further, non-reproductive crayfish with high energy stores had a higher metabolic rate than reproductive crayfish. This is an indication that high energy stores are needed to fuel growth in the non-reproductive form and thus resulting in higher metabolic demands. Understanding the links between physiology and behavior not only has important implications for the evolution of life history traits but may also provide insight into the dynamics of range expansion in this invasive crayfish species.