Master of Sciences, Case Western Reserve University, 2022, Biology

Matrix population models are a prevalent and useful tool for modeling populations in ecology. Stochasticity, meanwhile, is used in ecological modeling to reflect the natural variability in any population's environment and demographic rates. In this thesis, I explore the role of stochasticity, or randomness, in ecological matrix models. Firstly, I use a Leslie-style matrix model to explore how variation in the carrying capacity of generalist avian predators suggests a mechanism by which developmentally synchronized cohorts of periodical cicadas, called “broods", overcome competitive exclusion by their parent brood, and thereby synchronize mass emergence in a different year. Then, I derive a method to analyze which sources of process noise contribute most strongly to state covariance in matrix models. We thus provide a method complementary to the population viability analysis that may help to reduce stochastic extinction risk, and apply the method to a species of conservation concern, the desert tortoise.

Committee: Karen Abbott (Advisor); David Gurarie (Committee Member); Peter Thomas (Committee Member); Gabriella Wolff (Committee Chair) Subjects: Applied Mathematics; Biology; Ecology

Master of Science, Miami University, 2005, Zoology

The purpose of this study was to examine some of the possible causes for the negative density-area relationship reported for the white-footed mouse, Peromyscus leucopus. I examined predation and food availability in three small and three large forest fragments. Giving up density trays and various odors were used to test the variation in foraging behavior in the presence of a predator odor. Nest boxes and counts of periodical cicada emergence holes were used to test the effects of an emergence of periodical cicadas on P. leucopus population densities. Predator odors had no effect on foraging behaviors. P. leucopus responded to indirect, but not direct, cues of predation. Estimated densities of periodical cicada emergence holes were strongly related to the relative population density of P. leucopus. Continued study of predation and food differences in forest fragments of different sizes is needed to further examine the negative density-area relationship of P. leucopus.

Committee: Douglas Meikle (Advisor) Subjects: