Department Chair

Dr. I. Martha Skerrett

Date of Award


Access Control

Open Access

Degree Name

Biology, M.A.


Biology Department


Dr. Randal Snyder

Department Home page

First Reader

Dr. Randal Snyder

Second Reader

Dr. Alicia Pérez-Fuentetaja

Third Reader

Dr. Thomas White


Understanding mechanisms that account for phenotypic variation has been of interest to biologists since the advent of Darwin’s theory of evolution by natural selection. It is now understood that adaptive divergence is a key driving force of intraspecific differentiation. Further, differences in habitat (e.g., flow regime, prey regime) have been shown to drive adaptive divergence in fish. For instance, fish inhabiting faster flowing water generally exhibit more fusiform bodies than their lake counterparts. Similarly, the partitioning of benthic and pelagic morphs generally results in smaller heads with the latter. This study used geometric shape analysis to assess morphological differences between emerald shiner (Notropis atherinoides) populations inhabiting the Niagara River, Lake Erie, and Lake Ontario. It was expected that emerald shiners inhabiting the two lakes would have more robust bodies and smaller heads. Conversely, river emerald shiners were expected to display more fusiform bodies with larger heads. The results of this study demonstrated that emerald shiners from Lake Erie and the Niagara River had a more robust average form than individuals from Lake Ontario. This suggests that factors other than flow regime may have been responsible for this divergence. Future studies should investigate the influence that predator communities may have on the morphological divergence between these Notropis atherinoides populations.