Honors Program

Honors in Biology

Date of Award


Thesis Professor(s)

Istvan Karsai

Thesis Professor Department

Biological Sciences

Thesis Reader(s)

Thomas F. Laughlin, Fred J. Alsop III


If two species are competing for a limited resource, the species that uses the resource more efficiently will eventually eliminate the other. This is known as the principle of competitive exclusion developed by Georgy Gause. To determine the effect of this competition, a simple three-dimensional model of a pond is created in which two species compete for a single source of energy (algae). The model is based solely on the conservation of the energy that flows through an ecosystem where primary production is the only source of energy. The first scenario tested is of two competing species with identical life histories; therefore it is predicted that one of the species will randomly become extinct. Another experiment demonstrates how the speed of extinction is dependent upon the energy input (external factors) of the environment. Results show a higher rate of life cycles and smaller fluctuation of population between life cycles in a higher energy input environment and slower but higher fluctuating life cycles in a low energy input environment. The introduction of a predator to the system shows that an additional level of hierarchy can have a short term stabilizing effect in populations of competing species with identical life histories. Predators cannot be too efficient due to the risk of prey depletion leading to predator extinction occurs. Stratification of the two competing populations was then added to further stabilize the populations causing coexistence within the simulation. Slight differences in life histories can create large differences in survival. The simulations include changing speed, size, and energy input. When referring to the different life histories model, one species with certain parameters competing with another species with different parameters may be more successful under a certain environmental condition and less successful under other conditions.

Document Type

Honors Thesis - Withheld

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