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Foraging, Diet, and Metabolism in a Generalist Predator
Laboratory experiments show that many factors, including taxonomic identity, traits, energetic states, and environmental conditions influence predator-prey interaction strengths. Despite this, we lack an understanding of foraging variation in natural systems, where many variables may simultaneously influence foraging. Here, I use a common arthropod predator (wolf spiders, Lycosidae) to explore drivers of foraging-associated variation in the field. Wolf spiders are ubiquitous, voracious generalist predators, making this family ideal for examinations of natural foraging variation. In Chapter 1, I assess how variation in individual foraging history, in addition to body mass and species identity, can help explain individual variation in metabolism (which both powers foraging and is powered by foraging). In Chapter 2, I introduce novel methods to estimate dietary composition from metabarcoding data, a key advancement that will enable more rigorous assessments of foragers’ diets in the field. Though I demonstrate this approach using wolf spider gut contents, these methods can be used to determine diet composition in any consumer studied with dietary metabarcoding, facilitating studies of interaction strengths and niche overlap in the field. In Chapter 3, I test how foraging differences between individuals and species (i.e., niche partitioning and intraguild predation) may allow multiple wolf spider species to co-occur, using stable isotope analysis, gut content metabarcoding, and the methods introduced in Chapter 2. I additionally explore how factors that underlie variation in foraging performance may explain how niches are partitioned or the extent to which individuals engage in intraguild predation, examining how drivers of individual predator-prey interaction strengths may explain diet—and therefore coexistence—of ecologically similar species. Together, these three chapters reveal drivers of the extensive variation exhibited by foragers in the field while underscoring how much of this variation remains unexplained.
Uiterwaal, Stella F, "Foraging, Diet, and Metabolism in a Generalist Predator" (2022). ETD collection for University of Nebraska - Lincoln. AAI29254074.