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Copyright © 2002
 


Teacher Background Information for
Population Dynamics-Hands-on
Simulation

Day 1 simulation:

Background:

This activity is one component of a unit on Ecology. Prior to the activity students have learned about Mendelian genetics, populations, food webs, natural selection, and computational modeling. The activity shows how all of the above processes converge to affect population dynamics in an ecosystem.

Engagement:

The hands-on simulation (based in part on lab from Lach, Michael, and Loverude, Michael. The American Biology Teacher. February, 1998. p132) .is explained to the students, and students are asked to write a hypothesis/prediction based on their background knowledge.

Materials:
  • For a class of 30 students -- Card templates (Microsoft Office version, Adobe Acrobat version)
    • 30 rabbit cards
    • 30 grass cards
    • 30 wolf cards
    • Chart for recording data for each generation

Lab set-up:

The teacher needs to establish the following groups for the simulation:

  • 8 students given grass cards
  • 8 students given wolf cards
  • 8 students given rabbit cards
  • Two students to act as actuaries and record data for each generation
  • Three students to act as morticians and reincarnation specialists to recycle the "dead"

Exploration:


Students conduct the following hands-on simulation:

  1. Ten students are given cards labeled grass, ten labeled rabbits and ten labeled wolves. They move randomly around the classroom, and when signaled, they compare cards with closest student.
    Rules of Engagement:
    • Rabbits and wolves must eat at least every other generation or they die
    • wolf -- rabbit = rabbit dies
    • wolf -- wolf = 1 baby wolf added
    • wolf -- grass = nothing happens
    • Rabbit -- rabbit = 1 baby rabbit added
    • Rabbit -- grass = grass dies
    • Grass -- grass = 1 baby grass added
  2. After each generation students show by hand count how many surviving members there are in each population and this is recorded by the actuaries. Students who have "died" report to the mortuary/reincarnation center where they are assigned new identities and re-enter the simulation.
  3. The simulation ends when two of the three populations are extinct.

Explanation:

Students graph data from charts, analyze the data, and evaluate their original hypothesis.
.

Day 2 simulation: Introduction of Fast Rabbit Gene

This activity is the same as the Day 1 simulation but a "fast rabbit" gene is introduced and the above items are modified with the following changes:

  1. Materials: add 1 group of 30 cards for "fast rabbits" (Microsoft Office version, Adobe Acrobat version)
  2. Exploration: add 2 students with "fast rabbit" cards
  3. Add to rules of engagement:
    1. Fast rabbit -- rabbit = coin toss to determine type of offspring produced
    2. fast rabbit--fast rabbit = add 1 fast rabbit
    3. Fast rabbit -- wolf = coin toss to determine if rabbit lives or dies
    4. Students repeat the above simulation but begin with even population numbers.
      Example: 5 wolves, 5 grasses, 5 rabbits, 5 fast rabbits

Extension:

  1. Students explore the effect extrinsic variables (climate and natural disasters) and intrinsic variables (reproductive rates, mutations and diseases) on population dynamics by use of computer models.
  2. Students reevaluate original hypotheses in light of new data.


Teaching tips:

Actuary Data: It is very efficient for data collection and relay to the rest of the class if a transparency is made of the actuary data charts, and the actuaries record the numbers for each trial of the simulation where appropriate. This can be shared with the class later, and the data transferred easily

Lab write-up: Each teacher may tailor the lab write-up to their individual preferences depending on level of class and time available. Graphs are highly encouraged for visual comparisons between these two simulations as well as for a later comparison to the computer model simulation results.

Analysis/Conclusion Questions: Additional questions can be added to this section from the Instructional Framework relating to modeling. This can be tailored to class level and time.

Lab Grading Rubric: Available to assist in grading labs

  • Acrobat version
    0
    1
    2
    3
    Preparation Not attempted. Missing a component. Problem defined is unclear, stated hypothesis or variables not complete, poor experimental method. Defines problem, formulates hypothesis with appropriate variables, designs experimental method.
    Data Collection Not attempted . Missing a component Data collected and recorded, raw data poorly organized and presented Data collected and recorded, raw data is organized and present.
    Data Analysis Not attempted. Missing a component. Processes raw data correctly, but data not presented appropriately. Processes raw data correctly, presents processed data appropriately.
    Conclusion Not based on data, not realistic. Somewhat based on data. Based on data, somewhat realistic. Well formed, based on data, realistic.

 

Actuary Data Tables

Simulation # 1: Normal population

Generation Wolves Rabbits Grass
start=P      
F-1      
F-2      
F-3      
F-4      
F-5      
F-6      
F-7      
F-8      
F-9      


Simulation #1: Uneven Populations

Generation Wolves Rabbits Grass
start=P      
F-1      
F-2      
F-3      
F-4      
F-5      
F-6      
F-7      
F-8      
F-9      

Simulation #2: Fast Rabbit Introduction-uneven populations (2 fast rabbits)

Generation Wolves Rabbits Fast Rabbits Grass
start=P        
F-1        
F-2        
F-3        
F-4        
F-5        
F-6        
F-7        
F-8        
F-9        

Simulation #2: Fast Rabbit Introduction-even populations

Generation Wolves Rabbits Fast Rabbits Grass
start=P        
F-1        
F-2        
F-3        
F-4        
F-5        
F-6        
F-7        
F-8        
F-9        

 

Student Handout


Population Dynamics: Hands-on Simulation
Normal Rabbits

Purpose:

Hypothesis/prediction

Procedure:

Data:

Simulation # 1: Normal populations

Generation Wolves Rabbits Grass
start=P      
F-1      
F-2      
F-3      
F-4      
F-5      
F-6      
F-7      
F-8      
F-9      


Simulation #1: Uneven Populations

Generation Wolves Rabbits Grass
start=P      
F-1      
F-2      
F-3      
F-4      
F-5      
F-6      
F-7      
F-8      
F-9      



Graphs:

Graph the population size dynamics over time for the above two simulations on different graphs. Use three colors to represent the three groups of organisms.

Analysis and conclusions:

  1. Which population decreased most quickly? Why did this happen?
  2. How did the decrease in one population affect the other two populations? Be specific giving data to support your answer.
  3. Reproductive potential is the ability of a species to populate an environment without any restrictions such as predators, nutrient limits, natural disasters, or disease. Did our simulation take into account reproductive potential? Explain your answer.
  4. Did any of the above graphs show characteristics of logistic or exponential growth curves? Support your answer with examples.

 


Population Dynamics: Hands-on Simulation
Fast Rabbit

Purpose:

Hypothesis/prediction

Procedure:

Data:

Simulation #2: Fast Rabbit Introduction

Generation Wolves Rabbits Grass
start=P      
F-1      
F-2      
F-3      
F-4      
F-5      
F-6      
F-7      
F-8      
F-9      

 

Simulation #2: Fast Rabbit Introduction

Generation Wolves Rabbits Fast Rabbits Grass
start=P        
F-1        
F-2        
F-3        
F-4        
F-5        
F-6        
F-7        
F-8        
F-9        

Graphs:

Graph the population size dynamics over time for the above two simulations on different graphs. Use three colors to represent the three groups of organisms.

Analysis and conclusions:

  1. How did the introduction of the fast rabbit to the food chain affect the dynamics of the three populations? Why do you think this happened?
  2. Compare this simulation to the first lab simulation without fast rabbits. How does the life expectancy change among rabbits, wolves, and grass? Why do you think this happened?
  3. List five factors which will impact these 3 populations but which could not be included in our simulation because of our limited ability in a hands-on activity (ex: grass reproduction rate).

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by the

National Science Foundation

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