Community Interactions: Competition and PredationActivities & Teaching Strategies
Active learning engages students directly with the dynamic relationships in ecological communities. By modeling competition and predation through simulations and data analysis, students move beyond memorization to observe firsthand how populations interact and adapt over time.
Learning Objectives
- 1Analyze data sets to compare the population dynamics of predator and prey species in a specific US ecosystem.
- 2Explain the mechanisms by which resource partitioning allows for the coexistence of competing species.
- 3Differentiate between interspecific and intraspecific competition, providing examples of each.
- 4Evaluate the impact of specific prey defensive adaptations on predator success and evolution.
- 5Predict the outcome of competition between two species given their resource needs and niche overlap.
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Ready-to-Use Activities
Graphing Lab: Predator-Prey Population Cycles
Using Hudson Bay Company records of lynx and snowshoe hare pelts (a classic proxy for population size), students graph both populations on the same axes and analyze the lagged oscillations. They identify which population leads the cycle, explain the cause-and-effect relationship that sustains the cycle, and predict what happens if a secondary prey source for lynx is added.
Prepare & details
Explain how the competitive exclusion principle shapes community diversity.
Facilitation Tip: During the Graphing Lab, circulate to ensure students correctly label axes and include a key for predator and prey lines before they start plotting data.
Setup: Open space or rearranged desks for scenario staging
Materials: Character cards with backstory and goals, Scenario briefing sheet
Simulation Game: Competitive Exclusion Experiment
Based on G.F. Gause's paramecium experiments, two 'species' of students compete for the same resource chips with slightly different success rates. After 10 rounds, students graph population sizes, observe competitive exclusion, and then modify the experiment by adding a second resource type to simulate resource partitioning and test whether coexistence becomes possible.
Prepare & details
Analyze how defensive adaptations in prey influence predator evolution.
Facilitation Tip: For the Competitive Exclusion Experiment, assign roles so students rotate between setting up trials, recording data, and analyzing results.
Setup: Flexible space for group stations
Materials: Role cards with goals/resources, Game currency or tokens, Round tracker
Gallery Walk: Coevolution in Action
Create stations featuring paired coevolved predator-prey relationships (cheetah and Thomson's gazelle speed, monarch butterfly and milkweed cardenolide toxins, mimic octopus and predators). At each station, students identify the evolutionary pressure, list one defensive and one offensive adaptation the relationship has produced, and note how removing one species would affect the other's evolution.
Prepare & details
Differentiate between interspecific and intraspecific competition.
Facilitation Tip: In the Gallery Walk, provide sentence starters on posters to guide students in writing specific examples of coevolution they observe.
Setup: Wall space or tables arranged around room perimeter
Materials: Large paper/poster boards, Markers, Sticky notes for feedback
Think-Pair-Share: Classifying Competition
Students receive six competition scenarios and classify each as interspecific or intraspecific. They explain to a partner why intraspecific competition is generally more intense (identical resource requirements) and discuss one example from a US ecosystem where intraspecific competition has shaped observable behavior or morphology.
Prepare & details
Explain how the competitive exclusion principle shapes community diversity.
Setup: Standard classroom seating; students turn to a neighbor
Materials: Discussion prompt (projected or printed), Optional: recording sheet for pairs
Teaching This Topic
Teaching this topic works best when students physically manipulate variables and observe immediate outcomes. Avoid relying solely on textbook examples; simulations let students test predictions and see exceptions like resource partitioning in real time. Research shows that students grasp the concept of dynamic equilibrium more deeply when they graph fluctuating populations themselves rather than reading about it.
What to Expect
Students will explain how competition and predation shape population cycles and community structure using evidence from their simulations and observations. They will also predict outcomes when species partition resources or face competitive exclusion.
These activities are a starting point. A full mission is the experience.
- Complete facilitation script with teacher dialogue
- Printable student materials, ready for class
- Differentiation strategies for every learner
Watch Out for These Misconceptions
Common MisconceptionPredators always reduce prey populations toward extinction.
What to Teach Instead
During the Graphing Lab: Students analyze real predator-prey oscillation data and adjust their line graphs to show how declines in prey lead to predator declines, then prey recovery. Point out the peaks and troughs to reinforce the cyclical nature of these interactions.
Common MisconceptionCompetition always results in one species winning and the other going extinct.
What to Teach Instead
During the Competitive Exclusion Experiment: After students observe competitive exclusion in the initial simulation, have them modify variables to include resource partitioning, such as different feeding times or microhabitats, and observe how coexistence becomes possible.
Common MisconceptionDefensive adaptations are always physical structures like shells or spines.
What to Teach Instead
During the Gallery Walk: Provide a set of adaptation examples that include behavioral strategies like alarm calls or feigning death. Have students sort these into categories and discuss which are most effective in different scenarios.
Assessment Ideas
After the Competitive Exclusion Experiment, provide two hypothetical species descriptions and ask students to predict whether the species would compete and if they could coexist through niche partitioning, using evidence from their simulation data.
After the Graphing Lab, pose the question: 'What would happen to the predator population if a new disease reduced the prey population by half?' Facilitate a class discussion where students use their graphs to justify their predictions.
During the Think-Pair-Share activity: Have students write a definition of interspecific and intraspecific competition on one side of an index card and provide a local example on the other side before pairing up to discuss.
Extensions & Scaffolding
- Challenge early finishers to design a new predator-prey scenario using the simulation software with altered starting populations or environmental factors.
- Scaffolding for struggling students: Provide a partially completed data table for the Graphing Lab with pre-labeled axes and one plotted point to reduce cognitive load.
- Deeper exploration: Have students research an example of character displacement in nature and present their findings with a visual aid during the Gallery Walk.
Key Vocabulary
| Competitive Exclusion Principle | The ecological rule stating that two species competing for the exact same limited resources cannot coexist indefinitely; one species will eventually outcompete the other. |
| Niche Partitioning | The process by which competing species use the environment differently in a way that helps them to coexist. This can involve using different resources, habitats, or times of activity. |
| Predation | An interaction where one organism, the predator, hunts and kills another organism, the prey, for food. |
| Coevolution | The process where two or more species reciprocally affect each other's evolution. This is often seen in predator-prey relationships, where prey develop defenses and predators develop ways to overcome them. |
| Interspecific Competition | Competition for resources that occurs between individuals of different species. |
| Intraspecific Competition | Competition for resources that occurs between individuals of the same species. |
Suggested Methodologies
Planning templates for Biology
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