Materials Included In Kit

Additional Materials Required

Prelab Preparation

Optional: Laminate multicolored wrapping paper to increase durability.

Safety Precautions

This laboratory activity is considered nonhazardous. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Beans may be saved for future use or discarded according to Flinn Suggested Disposal Method #26a.

Lab Hints

• Enough materials are provided in this kit for 32 students or eight groups of four students each. All materials are reusable. This activity may be completed in one 50 minute class period and the Post-lab Questions completed the day after the lab.
• Prior to beginning the activity, you may want to empty the individual bags of seed into separate containers for easier access by all members of each group. Approximately 112 g (4 oz) per student should be sufficient to complete the activity.
• If “hunting” for three seconds seems to be too much time for certain “environments,” feel free to reduce “hunting” time to two seconds.
• Randomly distribute the “environments” to each group to ensure greater diversity in the overall results.
• To simulate the many different environments that are found on Earth, you may want to collect additional pieces of multicolored paper in addition to the ones included in the kit.
• Laminating the wrapping paper will preserve it for long-term use.
• Since all groups are basically doing the same thing, at some point during the data collection give each group some environmental factor that will affect either one or both populations (i.e., drought, flood, fire, disease, overgrazing, hunting or trapping). Prey and/or predators should be removed or added accordingly.
• Students should record the environmental change that is given to them at the bottom of the data table and indicate when that change occurred by writing a star (*) next to a generation number in the left-hand margin.
• When all data are collected, display each group’s “environment” in front of the class and write the highest number of prey survivors below it. Students will need these data to answer Discussion Questions 4a, b and c.
• You may want to discuss the difference between linear and exponential growth rates using students’ graphs.
• Take time to have student groups report and comment on their results (Questions 1–3) then, discuss the answers to Questions 4a–c and the four questions in the introduction:

1. How are an organism’s adaptations acquired?
2. Based on the results of this activity, what happens when something in an organism’s environment changes?
3. When environmental changes take place, do organisms leave the area, do they just die and become extinct, or do organisms develop characteristics they didn’t already have to enable them to survive and reproduce?

Sample Data

(Student results may vary. Data do not include any external environmental factors.)

Answers to Questions

1. Graph the data from the table above for all 25 generations. Place the predator and prey data (found on the first two columns) on the same axis (x-axis) so that the relationship between predator and prey can be easily observed.

2. Did some species of “prey” survive and produce more offspring in your group’s environment than other prey in the same environment? If yes, why? If no, why not?

Student answers will vary.

3. How did the environmental factor that was given to the group by the instructor affect the prey and/or predator populations? (Briefly describe what happened.)

Student answers will vary.

4. After graphing the data, explain the relationship between predators and prey as shown by the graph. Be specific.

Although the number of animals of prey and predators are different their populations mirror each other. If the prey population increases so does the predator and vice versa. If there is less prey to eat the predators start to die off as there is no food to eat.

5. 1. Did the prey species that survived and produced the most offspring in one group’s environment survive and produce the most offspring in another group’s environment? Why or why not?

      Student answers will vary.

   2. How does the answer to 5a relate to what happens to populations of organisms in nature when their habitat is changed or destroyed?

      Student answers will vary.

   3. Does this ability to survive and produce many offspring in spite of environmental changes apply to human populations as well? Give a specific example from events in the world to explain your answer.

Student answers will vary.

References

This simulation is an adaptation of a game produced many years ago by Urban Systems Inc. for use in the home. This activity may serve as an introduction to how computers are used to model real life situations.

Introduction

The 19th century naturalist, Charles Darwin, observed that organisms in nature appear to be well-adapted to their habitat. This observation posed the question of how this phenomenon may have occurred. Conduct this activity to simulate the factors Darwin used to propose his theory of natural selection.

Concepts

• Natural selection

• Survival adaptations

Background

On November 24, 1859, Charles Darwin (1809–1882) published On the Origin of Species by Means of Natural Selection. The Origin of Species focuses on two main points. First, Darwin presented Natural Selection to account for supporting evidence that species inhabiting Earth today descended from ancestral species. Secondly, Darwin proposed a mechanism for evolution. The basic premise of natural selection is that populations of organisms will change over time if individuals with certain heritable traits that are beneficial for survival survive in greater numbers than those without the trait. They are able to leave more offspring resulting in a larger concentration of that trait in the population. Over time natural selection results in evolutionary adaptation. Evolutionary adaptation is a prevalence of inherited characteristics that benefit organisms’ survival and reproduction in specific environments.

It seems that all organisms have “built-in” genetic characteristics that enable them to live in particular habitats. For example, fish live in water because their gills allow them to extract oxygen from the water. Whales and other mammals live in the water because they can stay submerged for long periods of time and then return to the surface to breathe oxygen from the air. Most birds fly because they have lightweight bones and feathers covering their wings. Adult toads can live away from water because they are able to absorb water from moist soil through their skin. Some plants have tiny “claws” that help them cling to hard surfaces like rocks or bricks. In addition, the color of many organism’s outer skin, feathers, fur, etc. allows them to blend in with the surrounding environment, improving their chances for survival.

Experiment Overview

This activity will assist in discovering what happens when both prey and predator species in the same environment attempt to do the same thing, that is, survive and pass their genes on to the next generation.

Materials

Safety Precautions

Once food-grade items are brought into the lab they are considered chemicals and should not be consumed. Wash hands thoroughly with soap and water before leaving the laboratory. Please follow all laboratory safety guidelines.

Procedure

Read the Procedure and Rules sections thoroughly before beginning.

1. For this simulation, each student in the group will be a different predatory animal and each will have a different primary source of food. The predator and their prey species are as follows:

1. Grackles (a large black bird similar to crows) eat Worms—represented by kidney beans.
2. Bats eat Moths—represented by black beans.
3. Barn owls eat Mice—represented by navy beans.
4. Bobcats eat Rabbits—represented by pinto beans.

2. Each person chooses one of the four food types.
3. Place the “environment/hunting territory” (colored paper) on a table or desktop.
4. Begin each “predator’s” hunting session as follows:

1. Remove three seeds from a container and place them in the environment.
2. The “predator” either tightly closes her/his eyes or is blindfolded while the other group members try to place the seeds in areas of the environment that will make it difficult for the “predator” to spot them easily.
3. After the seeds are placed and a group member says, GO, the “predator” opens her/his eyes and has three seconds to try and pick up all three “prey” species.
4. Record the results of the hunting session in the data table as indicated by the column headings.

Predator Rules

• When hunting, No raking across the paper is allowed!
• Hunting must stop when time is called!
• Only prey held in the fingers and off the paper can be counted as captured.
• Predators only reproduce if three prey are captured each hunting session.

1. If only two prey are captured, the predator survives but does not reproduce.
2. If only one prey is captured, the predator dies.

• Start each hunting session (generation) with one predator. If no predator exists from the previous generation, assume one new predator migrates into the area.
• As predator numbers increase, all predators must be allowed to hunt prey before the next predator in the group begins to hunt. Therefore, as in step 4b, while the predator’s—parent plus offspring—eyes are closed, group members arrange and try to “hide” all the prey.
• When more than one predator is “hunting”—parent and offspring—“hunting” time is reduced to two seconds (x) the total number of predators (i.e., 2 seconds x 12 predators = 24 seconds).
• After all predators have hunted each session, the Total Prey Eaten column of the data table should be filled in with the total number of all prey caught by both “parent” and “offspring” predators.
• Use the numbers in the Total Prey Eaten column to determine how many predator offspring will be produced before the next hunting session.

Prey Rules

• All surviving prey species reproduce by doubling. Multiply the number in the Prey Survivors column of the data table by two. This is the number that will be entered in the Prey Type column to begin the next hunting session/generation.
• A minimum of three prey must be in the environment to start each hunting session. If and when the prey are wiped out, assume new prey species migrate into the area and start over.
• If a point is reached, during the game, where no more prey is available to put into the environment (i.e., there are no more of your type of seeds), stop and complete the data table mathematically.

General Rules

• After each “predator” in the group has completed a hunting session, the next person (predator) in the group completes his/her hunt as described and fills in the data table.
• Continue hunting—steps 4a to 4d—for 15 generations, if possible. Complete the remaining 10 rows (25 total) of the data table mathematically using the percentages established in the previous rows.
• Each student will graph his own prey/ predator data (see Analysis). However, the Discussion Questions may be answered with the help of other group members.

Student Worksheet PDF

10614_Student1.pdf