How does alteration of chemical information affect assessment in male and female crayfish, Orconectes rusticus?
This dissertation builds on our limited understanding of female agonsim through the lens of assessment and the information driving these behavioral strategies. While empirical studies have demonstrated differences in winning probabilities and contest duration for male and female intrasexual contests, we know very little about the rules dictating differences in behavioral strategies and information used in these contests (Rosvall, 2011). The work outlined in this dissertation fills these gaps in knowledge by examining (1) sex-based differences in behavioral response to a signal within agonistic contests, (2) the effect signal removal on assessment in intersexual contests, and (3) sex-based differences in population level assessment strategies under differing social and environmental contexts.
I used crayfish as my model organism due to their well-studied aggressive behaviors and the propensity of both sexes to engage in inter- and intrasexual interactions. Because of their heavy reliance on chemical information across many aspects of their behavior, I first examined differences in male and female crayfish contest strategies in light of differential use of and response to chemical stimuli. Chemical information (i.e. urine) release and subsequent behavioral changes were quantified across male and female inter- and intrasexual contests, revealing that the behavioral response to this urine release differed based on opponent sex and relative size (Wofford et al., 2017). In line with previous studies, mixed sex contests seemingly followed a different set of rules and contest resolution than male or female same sex contests. The second aim of this dissertation further examined these differences by blocking chemosensory ability in mixed sex contests. Intersexual contest duration was significantly impacted by the sex of the lesioned opponent. Specifically, male lesioned contests were relatively unaffected by impaired chemosensation while female lesioned contests showed significant shifts in duration. Furthermore, the assessment strategy in place differed based on which sex had access to chemical information. In the final aim, I explored sex-based assessment differences due to alteration of social and environmental context. Artificial populations that varied in sex composition (male or female population), strength ratio (weak or strong skewed populations), and resource availability (i.e. resource value) demonstrated significant variation in assessment strategies in place. These findings confirm previous work that (1) suggests assessment fluidity across environmental and social contexts and (2) posits that the rules dictating male and female contest strategies significantly differ.