Natural Selection of Peppered Moths (Jason Elliott)

Title: Natural Selection of Peppered Moths

Principle(s) Investigated:

Describe the importance of coloration in avoiding predation.

Relate environmental change to changes in organisms.

Explain how natural selection causes populations to change.

HS-LS4-4. Construct an explanation based on evidence for how natural selection leads to adaptation of populations.

HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in: (1) increases in the

number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other

species.

Materials:

White Paper

News Paper

30 Small White Paper Circles

30 Small Newspaper Circles

Tweezers

Clock or Online Stopwatch

Handout

Computer

Internet Access

Procedures:

Simulation 1

1. Choose one person in the group to be the “bird predator”.

2. Place a sheet of white paper on the table and have one person spread 30 white circles and 30 newspaper circles over the

surface while the “predator” isn't looking.

3. The "predator" will then use tweezers to pick up as many of the circles as he can in 15 seconds. Use a clock or

Online Stopwatch

4. Record your results in the data table under Trial 1 on your handout.

5. Repeat steps 2 – 3 again. Record your results in the data table under Trial 2.

6. Place a sheet of newspaper on the table and have one person spread 30 white cutouts and 30 newspaper cutouts over the

surface while the “predator” isn't looking.

7. The "predator" will then use tweezers to pick up as many of the circles as he can in 15 seconds. Use a clock or

Online Stopwatch

8. Record your results in the data table under Trial 3.

9. Repeat steps 6 – 7 again. Record your results in the data table under Trial 4.

10. Enter your data into the form.

11. Examine the entire class data results.

Simulation 2

1. Each student should go to the Peppered Moth Simulation website on their individual computer.

2. Click on the "Life Cycle" circle on the left, then read about the life cycle of the Peppered Moth. Click on the arrows until you

reach the end.

3. Click on the "Impact of Pollution" circle, then read about how pollution affected peppered moths in England. Click on the arrows

until you reach the end.

4. Click on the "Kettlewell's Experiments" circle, then read about Dr. Henry Kettlewell. Click on the arrows until you reach the end.

5. Click on the "Bird's Eye View" circle, then read through the directions of the simulation. Click on the arrows until you reach the

"Choose a Forest Menu."

6. Click on the "Light Forest" circle to start the simulation. Move your cursor to move your bird and click to eat the moths. (Crunch

sound = moth eaten; tweet = missed moth)

7. Record your results on the data table under Light Forrest.

8. Click on the circle at the bottom of the screen to return to "Bird's Eye View." Repeat step 5.

9. Click on the "Dark Forrest" circle to start the simulation. Move your cursor to move your bird and click to eat the moths.

(Crunch sound = moth eaten; tweet = missed moth)

10. Record your results on the data table under Dark Forrest.

Questions

1. After completing both simulations, answer the questions in the Quickwrite

Student prior knowledge:

Natural selection is also known as Survival of the Fittest: those better suited (fit) for their environment survive; those that are not suited (not fit) die and do not reproduce. Natural selection works because there are many struggles for survival: organisms are constantly competing for food, space, mates, shelter, escape, etc. Natural selection is also known as Survival of the Fittest: those better suited (fit) for their environment survive; those that are not suited (not fit) die and do not reproduce. Fitness is the result of the accumulation of adaptations: any inherited characteristic that increases an organisms chance for survival in its environment. Camouflage is when a species phenotype blends in with that of its surroundings. Predators can not easily find the organism, thus enabling it to survive and reproduce.

Explanation:

Students will be given 30 light moths (white hole punch circles) and 30 dark moths (newspaper hole punch circles) as well as a light tree (white paper) and a dark tree (newspaper). These simulations will help students be able to desribe the importance of coloration in avoiding predation. They will be able to relate environmental change to changes in organisms. A history lesson on the industrial revolution will give students a better grasp on how sudden changes in the environment can speed of the evolutionary process. The first simulation will give the students a hands on chance to see how the white circles (white moths) are easier to be seen on the newspaper background than on the white paper and vice versa. The idea of camoflage should be easier to accept when seeing it first hand. The computer simulation is an even better experience to further solidify the idea of camouflage, since the moths are actually moving while you try to catch them with your cursor. The form/data table will then allow students to quickly see the results from the rest of the class. The questions on the quickwrite will then assess whether the students fully grasp the concepts of natural selection and camouflage.

Questions & Answers:

1. What did the experiment show about how prey are selected by predators?

A. Predators can only eat the prey that it can find. In the experiment, it was easier to find (eat) the moths that were not

camoflaged to the given background.

2. What moth coloration is the best adaptation for a light (white paper) background? Use your results to support your answer.

A. The light moths (white circles) are camoflaged to the light (white paper) background, so they are less likely to be eaten by predators. The number of white circles chosen by the "predator" in Trial 1 and 2 is less than the newspaper circles.

3. What moth coloration is the best adaptation for a dark (newspaper) background? Use your results to support your answer.

A. The dark moths (newspaper circles) are camoflaged to the dark (newspaper) background, so they are less likely to be

eaten by predators. The number of newspaper circles chosen by the "predator" in Trials 3 and 4 is less than the white

circles.

4. What would you expect the next generation of moths to look like after Trial 1? What would you expect the next generation of

moths to look like after Trial 3? Why do you think this?

A. The next generation of moths following Trial 1 will most likely contain more white moths, because there are now less dark moths. The next generation of moths following Trial 3 will most likely contain more dark moths, because there are now less light moths. Less of a particular colored moth will lead to a smaller frequency of that genotype in the gene pool.

5. How does the simulation model natural selection?

A. The simulation demonstrated how camoflaged moths have a higher fitness in their environment, therefore they are more

likely to survive to reproduce and pass on their genes to future offspring.

Applications to Everyday Life:

Variety of life forms: This simulation helps explain the variation of all organisms including ourselves. Natural selection can help explain how life started with a single cell and evolved into millions of different species over time.

Allergies: It can help explain how allergies such as lactose intolerance and peanut allergies have become prevalent in our society.

Illnesses: Students can learn about how infectious diseases can evolve, so that they can no longer be cured by certain medicines. They can learn why their are different strains of the flu and why scientists have to make an educated guess on what strains to protect against on any given year.

Photographs: