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Adaptive Foraging in a Generalist Predator: Implications of Habitat Structure, Density, Prey Availability and Nutrients

Schmidt, Jason M.
http://rave.ohiolink.edu/etdc/view?acc_num=miami1312815757

Abstract Details

2011, Doctor of Philosophy, Miami University, Ecology, Evolution and Environmental Biology.
Adaptive foraging is a recent theoretical synthesis linking foraging decisions to the structure and functioning of ecological communities. However, empirical research is required to characterize the consequences of different environmental challenges on organisms foraging behavior. The goal of this dissertation was to explore ecological factors that are responsible for variation in the foraging behavior of a common generalist predator, the wolf spider Pardosa milvina. I conducted four studies to investigate aspects of the adaptive foraging framework, space use and prey selection. I first explored the how habitat structure affects density and foraging ability. Spiders preferred areas containing more structural features, but contrary to predictions, they preferred patches low in prey. Foraging rate was reduced by some habitat features, and habitat structure lowered interference levels between spiders. I examined the role of prey abundance and predator abundance on interference determined by changes in patch leaving frequency and in their functional response. While prey abundance had strong effects on the tendency to leave patches, indicating the importance of prey to predator patch use, increasing the abundance of predators led to increased dispersal rates and interference. I used a two-pronged approach to understanding prey selection in this spider. In one set of experiments I measured changes in consumption of a target prey group in the field using a molecular probe. Although there was variation in the proportion of spiders testing positive for prey, the consumption of prey did not follow strict frequency dependence expected for generalist species. In a second set of experiments I tested for one prey characteristic, nutrient quality, to help explain predation rate and prey choice. The functional response of spiders to different prey nutrient compositions was comparable, but when spiders were fed on a prior nutrient enhanced diet, spiders killed a significantly greater number of prey over densities of prey offered. Prior diets also influenced prey choice. Taken together, these results paint this predator as an adaptive forager that makes foraging decisions based on multiple stimuli in the environment.
Ann Rypstra (Advisor)
A. John Bailer (Committee Member)
Alan Cady (Committee Member)
Thomas Crist (Committee Member)
Michael Vanni (Committee Member)
148 p.
Ecology
agroecosystem; C:N; density dependent interactions; ELISA; functional response; interference; habitat selection; food-webs; model selection; molecular analysis; prey selection; refuge; space use; spiders

Recommended Citations

Citations

  • Schmidt, J. M. (2011). Adaptive Foraging in a Generalist Predator: Implications of Habitat Structure, Density, Prey Availability and Nutrients [Doctoral dissertation, Miami University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=miami1312815757

    APA Style (7th edition)

  • Schmidt, Jason. Adaptive Foraging in a Generalist Predator: Implications of Habitat Structure, Density, Prey Availability and Nutrients. 2011. Miami University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=miami1312815757.

    MLA Style (8th edition)

  • Schmidt, Jason. "Adaptive Foraging in a Generalist Predator: Implications of Habitat Structure, Density, Prey Availability and Nutrients." Doctoral dissertation, Miami University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=miami1312815757

    Chicago Manual of Style (17th edition)

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© 2011, all rights reserved.
This open access ETD is published by Miami University and OhioLINK.