Competitive Exclusion Principle

The competition simulation allows students to test an example of the competitive exclusion principle. This is the idea that two species cannot coexist if they have the same niche. The principle was demonstrated in a classic experiment with P. aurelia and P. caudatum. There is a Glencoe virtual lab that takes students through a version of this experiment.

The Biology Simulations competition simulation uses a fictional scenario with two plant-eating organisms and a plant population. This simulation varies from the Glencoe version in that it is much faster to run, so multiple trials can be completed by each student. It also has a greater amount of random variation, which increases the value of running multiple trials and finding an average. Finally, students are able to control the amount of food available in the system and the starting populations for both organisms, which introduces additional avenues of experimentation and discussion.

The competition simulation with the blue population set to 0.

Competition simulation with both organisms starting at the same population size

The available worksheets (Google doc versions)provide a guided lab with a procedure for students to follow and charts for data collection. The worksheets include a followup section that asks students to research the P. aurelia and P. caudatum experiments and discuss competition in ecosystems.