Date of Award

Spring 1999

Document Type

Restricted Thesis

Terms of Use

© 1999 Andrew A. Caffrey. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts



First Advisor

Amy Cheng Vollmer


A model of two-species competition was developed from Gause's model by assuming that the two species did not interfere with each other's growth apart from resource-based competition. Two species of bacteria, Escherichia coli and Serratia marcescens, were used to test the model. The model was useful for predicting the population levels of the two species from the start of exponential phase to the start of stationary phase (R² = 0.653 for E. coli, and 0.680 for S. marcescens). This model differed from the original because it was able to predict the population levels solely based on information from the species' growth separately, and because it predicted stable equilibrium points. This theoretical conclusion suggests that competitive exclusion holds only when interference competition occurs.