Date of Graduation

Summer 2023


Master of Science in Biology



Committee Chair

Sean Maher


Ecological community studies provide insights on how species interact with biotic and abiotic factors in an ecosystem. Community assembly is dynamic and often mediated by stochastic processes or deterministic properties. Establishing patterns in community composition could help to predict the suitability of a patch, which is crucial in endangered ecosystems. Small mammals are a model indicator for community change as their populations experience perplexing fluctuations. Many mechanisms have been proposed to drive small mammal species composition, but inconsistencies in past studies warrant further investigation. A previous study on prairie patches in Missouri revealed that there was an unknown catalyst for species composition. Following this study, small mammal sampling was completed across 15 prairie patches. Additionally, vegetation characteristics and other environmental data were collected to evaluate patch dynamics. Analysis of these variables, in combination with mammal data, may provide a more robust understanding of community responses to prairie attributes. Sherman live traps were used to capture 217 individuals that consisted of 7 species, with Peromyscus maniculatus and Microtus ochrogaster facilitating a two-species system. Two distinct community types were found across sites and were determined by the dominant species. Ordination plots and variation algorithms were used to quantify community structure. Heterogeneity in environmental predictors did not drive community assembly, but some patch attributes were found to explain some of the variability. Outcomes suggest that small mammal communities are forming stochastically, and this stochasticity could be driven by unknown deterministic conditions. To uncover the possible mechanism behind community makeup, a larger sample size and annual sampling must be complete. Estimates can then be made on whether deterministic variables, stochasticity, or a combination of the two are influencing community composition. Further offering applicable practices that would benefit biodiversity maintenance in one of the most imperiled ecosystems in the country.


community ecology, small mammals, prairie, habitat heterogeneity, stochasticity, species composition, vegetation characteristics, metacommunity, deterministic

Subject Categories

Environmental Health and Protection | Environmental Sciences | Natural Resources and Conservation | Other Environmental Sciences


© Sofia L. Orlando

Open Access