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Pavlic, Theodore P.Optimal Foraging Theory Revisited
Master of Science, The Ohio State University, 2007, Electrical Engineering
Optimal foraging theory explains adaptation via natural selection through quantitative models. Behaviors that are most likely to be favored by natural selection can be predicted by maximizing functions representing Darwinian fitness. Optimization has natural applications in engineering, and so this approach can also be used to design behaviors of engineered agents. In this thesis, we generalize ideas from optimal foraging theory to allow for its easy application to engineering design. By extending standard models and suggesting new value functions of interest, we enhance the analytical efficacy of optimal foraging theory and suggest possible optimality reasons for previously unexplained behaviors observed in nature. Finally, we develop a procedure for maximizing a class of optimization functions relevant to our general model. As designing strategies to maximize returns in a stochastic environment is effectively an optimal portfolio problem, our methods are influenced by results from modern and post-modern portfolio theory. We suggest that optimal foraging theory could benefit by injecting updated concepts from these economic areas.

Committee:

Kevin Passino (Advisor)

Keywords:

robotics; automation; autonomous vehicles; behavior; behavioral ecology; intelligent control; portfolio theory; modern portfolio theory; MPT; post-modern portfolio theory; PMPT; optimal foraging theory; OFT; optimal diet selection; predator; prey

Kinney, Kaitlin AlyseThe role of biotic resistance through predation on the invasion success of the green porcelain crab (Petrolisthes armatus) into nearshore oyster reef communities.
Master of Science, The Ohio State University, 2017, Environment and Natural Resources
The northward spread of the non-native, invasive filter feeding crab Petrolisthes armatus into oyster reef communities along the Southeastern US is hypothesized to be limited by cold snaps associated with northern winters. However, several native predators in oyster reefs have been shown to consume this abundant and profitable prey item, suggesting that biotic resistance through predation may be an additional factor limiting its northward spread. My objectives were to 1) determine if the per capita predation risk exerted by native predators might be a factor that explains the current distribution of P. armatus, and 2) test whether the relative abundance of alternative native prey affects the consumption and preference of P. armatus by a native predatory crab Panopeus herbstii. I conducted a field study to quantify predation risk across 8 invaded estuary sites from St. Augustine, FL to North Inlet, SC and conducted a lab experiment to quantify the consumption of P. armatus when in low to high abundance relative to alternative native prey. While predation rates were high (68.2 – 98.2%) across sites, there was no relationship between predation and latitude across the 8 invaded estuaries. Furthermore, while P. herbstii increased consumption of P. armatus in response to increased abundance in the tank, P. herbstii always showed a preference for native prey regardless of its relative abundance. Overall, I found no evidence of biotic resistance through predation, suggesting that native predators do not prevent the spread of P. armatus and this species is likely to continue its expansion into northern waters as sea temperatures increase with climate change.

Committee:

Lauren Pintor, Dr. (Advisor); Stuart Ludsin, Dr. (Committee Member); Christopher Tonra, Dr. (Committee Member); James Byers, Dr. (Committee Member)

Subjects:

Ecology; Environmental Studies; Natural Resource Management

Keywords:

biological invasion; biotic resistance; green porcelain crab; Petrolisthes armatus; geographic range; nonnative species; predator-prey; optimal foraging theory

Sayers, Kenneth A.Optimal foraging on the roof of the world: A field study of Himalayan langurs
PHD, Kent State University, 2008, College of Arts and Sciences / School of Biomedical Sciences
Himalayan gray langur monkeys represent one of few primates able to live in temperate or alpine habitats, and little is known about their feeding behavior. I collected behavioral and ecological data on Himalayan langurs living above 3000 m elevation at Langtang National Park, Nepal in 2000 and from 2002-2004. Methods included scan sampling, continuous focal sampling, phenological sampling, and nutritional analysis of foods. Himalayan langurs were found to be largely folivorous, but with marked seasonal changes in diet, activity patterns, and travel distance in relation to changes in food availability or consumption. In addition, the monkeys frequently engaged in extractive foraging, the exploitation of hidden foods, such as the digging of underground storage organs. Such behavior has been considered rare in the Colobinae and is the focus of one major model of primate intelligence. The classical prey model from foraging theory, as modified for patch choice, consistently underestimated langur diet breadth irrespective of whether energy or crude protein was utilized as currency. Other predictions of the model were at least qualitatively supported, and it performed best when its assumptions were more closely approximated. The social prey model, in contrast, predicts differing behavior for group versus solitary foragers while in a depleting patch with two food types. In agreement with the model, langurs were more likely to take two food types from a patch when residence times were longer, and the profitability of the first food taken (energy/time) was significantly greater in social but not solitary foragers. Contrary to the model, the rate of gain before switching to the less profitable food was not lower in increasingly competitive situations. Taken together, these results have implications for current models of primate socioecology and cognition, and for the applicability of simple mathematical models to primate feeding behavior.

Committee:

Marilyn A Norconk, PhD (Committee Chair); C. Owen Lovejoy, PhD (Committee Member); Richard S Meindl, PhD (Committee Member); Charles R Menzel, PhD (Committee Member)

Subjects:

Animals; Biology; Physical Anthropology; Psychology; Zoology

Keywords:

theoretical evolutionary ecology; optimal foraging theory; diet; nutrition; ranging; cognition; colobine monkeys; Semnopithecus entellus

Hostert, Lauren ElizabethThe role of individual variation in the consumption of non-native prey: implications for the evolution of diet specialization and biological invasions
Master of Science, The Ohio State University, 2014, Environment and Natural Resources
Abundant non-native species frequently cause changes in natural environments by altering the composition and abundances of native species. One explanation for why non-native species are able to reach higher densities outside of their native range is because they escape their natural enemies (i.e. Enemy Release Hypothesis). Although the release of non-native species from their natural enemies may be due to lower densities or diversity of predators, parasites or pathogens, there are many alternative mechanisms that can reduce the predation pressure that a non-native species may experience following introduction into a new environment. In this study, I examined how individual variation in diet, morphology, competitive ability (i.e. aggression) of a native predator (common mudcrab, Panopeus herbstii), along with the relative energetic value of alternative prey contributes to the consumption of a recently introduced, non-native prey species (green porcelain crab, Petrolisthes armatus). Specifically, I: 1) quantified within-population variation in diet breadth and competitive ability of native P. herbstii predators, 2) evaluated the influence of competitive ability on within-population variation in diet and the consumption of non-native prey, P. armatus , and 3) compared the relative caloric densities of the native prey species of P. herbstii (G. demissa, C. virginica, and E. depressus) with that of the non-native prey P. armatus . AIC model comparisons indicated that predator sex, aggression, and competitor presence were the most important factors influencing diet specialization of P. herbstii predators, wherein predators that exhibited specialist diets were female and more aggressive. Individual P. herbstii predators also tended to exhibit specialist diets in the presence of a competitor. Individuals that specifically specialized on P. armatus were also female and more aggressive, but additionally, larger individuals. Individual P. herbstii predators generally, displayed more specialized diets on P. armatus in the absence of a competitor. The total number of P. armatus consumed was best explained by sex and size, whereby females and larger individuals consumed greater numbers of P. armatus. Also, in the presence of no alternative prey, females and smaller individuals consumed great quantities of P. armatus. Results from the oxygen bomb calorimetry analysis indicated that non-native P. armatus and native ribbed mussels Geukensia demissa have similar specific energies that are significantly greater than native eastern oysters Crassostrea virginica and depressed mud crabs Eurypanopeus depressus (which are not statistically different from one another). Overall, these results demonstrate that there is considerable individual variation in diet (i.e. some individuals are specialists, some generalists) and the consumption of P. armatus among the tested population of P. herbstii predators. P. armatus is a considerably profitable prey type compared to native prey yet only a sub-set of the population including females consumes P. armatus in large proportions. This gives some insight as to why P. armatus has been able to establish and maintain high population densities in this area but it produces more questions regarding why some individuals continue to not consume this abundant, profitable prey item.

Committee:

Lauren Pintor, PhD (Advisor); Elizabeth Marschall, PhD (Committee Member); Mazeika Sullivan, PhD (Committee Member)

Subjects:

Behavioral Sciences; Biology; Ecology; Environmental Science

Keywords:

non -native prey; optimal foraging theory; diet breadth; enemy release hypothesis