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					                         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
    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:
   1. 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”
   2. Exploration: add 2 students with “fast rabbit” cards
   3. Add to rules of engagement:
        Fast rabbit -- rabbit = coin toss to determine type of offspring produced
        fast rabbit--fast rabbit = add 1 fast rabbit
        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
                                Actuary Data Tables

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
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
                        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

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           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

  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).
                                             Name(s)

                                LAB REPORT

                                    RUBRIC


                   0                  1                 2                     3
PREPARATION Not attempted.      Missing a        Problem           Defines problem,
                                component.       defined is        formulates hypothesis
                                                 unclear, stated   with appropriate
                                                 hypothesis or     variables, designs
                                                 variables not     experimental method.
                                                 complete, poor
                                                 experimental
                                                 method.

DATA           Not attempted    Missing a        Data collected    Data collected and
  COLLECTI                      component.       and recorded,     recorded, raw data is
  ON                                             raw data poorly   organized and
                                                 organized and     present.
                                                 presented
DATA           Not attempted.   Missing a        Processes raw     Processes raw data
  ANALYSIS                      component.       data correctly,   correctly, presents
                                                 but data not      processed data
                                                 presented         appropriately.
                                                 appropriately.

CONCLUSION     Not based on     Somewhat         Based on data,    Well formed, based
               data, not        based on data.   somewhat          on data, realistic.
               realistic.                        realistic.

				
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posted:11/20/2011
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