Mechanisms Affecting Predation Success In Wolf Spiders
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Predator-prey interactions play a role in community structure through a variety of different mechanisms including direct consumption, density-mediated indirect effects, and trait-mediated indirect effects. Understanding factors that can influence the efficacy of direct consumption on prey populations can help us to identify the strength of the impact predators can have on lower trophic levels. My dissertation research focuses on how mechanisms like sexual dimorphism, impaired body condition, and starvation stress alter how effective an intermediate predator (i.e. a predator that occupies an intermediate position in the food web) can be in direct consumption of prey. Using wolf spiders as my model, and a combination of laboratory experimental foraging trials and field experiment approaches, I assessed the effectiveness of spiders as predators. My main questions were how sexual dimorphism and limb autotomy affect predatory behaviors in wolf spiders. I also examined the effect of starvation on fitness and immunological trade-offs using biochemical immune assays This research reveals that female wolf spiders are more effective at direct consumption of prey than males due to a combination of body size, trophic morphology, and behavioral dimorphisms. Limb autotomy had no significant effect on foraging success in wolf spiders, although there was a trend of leg autotomy having a negative impact on prey capture ability. Lastly, starvation of spiders leads to an energetic trade-off where individuals appear to sacrifice physiological condition for investment into immune defense. Findings from this dissertation can be utilized to help further our understanding of how predator-prey interactions shape community structure.