Peppered Moth Survey Lab

Peppered Moth Survey Lab

Problem: What is the relationship between environmental changes and the color variation of the peppered moth?

Introduction:

Industrial melanism is the term used to describe the adaptation of darkening by an organism in response to industrial pollution. One example of rapid industrial melanism occurred n the peppered moth, Biston betularia, in the area of Manchester , England from 1845 to 1890.

Before the Industrial Revolution, the trees in the forest around Manchester were light grayish-green due to the presence of lichens on their trunks. Peppered moths, which lived in the area, were light-colored with dark spots. Their coloring served as camouflage against predators, especially birds. As the industrial revolution progressed, the trees became covered with soot, which turned the trunks dark. Over a period of 45 years, a change took place in the peppered moth population in this area.

In this investigation, you will simulate a predator-prey situation and determine if color contrast has an effect on the ability of a predator to rapidly locate prey. In the second part of the investigation, you will study the data on peppered moth coloration as tactually reported over the course of several years. You will then determine the relationship between the environmental changes and the color variations of the peppered moths by using the research data to graph the results of an environmental adaptation.

Materials:

Sheet of newspaper 30 white paper disks, punched out of white paper

Sheet of white paper 30 newspaper disks, punched out of newspaper

Graph paper pencils, 2 different colors of lead (for graphing)

Forceps lab notebook

Hypothesis: Based on your background knowledge, make a hypothesis as to what type of moths you are most likely to capture on both types of backgrounds, the white paper and the newspaper.

Procedure

Part A

1. You will use the discs of white paper and newspaper to simulate prey. The paper discs will be placed on backgrounds that wither match or contrast with them. You will use forceps to simulate a bird’s beak and capture as many of your prey as possible in 15 seconds.

Place a piece of white paper on your lab desk. While your teammate is looking away, scatter 30 white and 30 newspaper disks on the paper. When your partner is ready with the forceps, let the hunt begin and start timing.

2. When 15 seconds have elapsed, count how many of each type of disk were picked up. Compare the number of captured disks of each type to the number that remained on the paper. Copy the data table from page 2 in your lab notebook. Record the numbers in the data table.

3. Replace the white paper with a sheet of newspaper. While your partner is looking away, scatter 30 newspaper disks and 30 white disks. Repeat the hunting procedure with your partner and record the number of disks picked up in the data table.

4. Change roles. You play the role of the predator, while your partner sets up the disks. Repeat steps 1 – 3 above.

Data table

Name / # of NP moths on NP / # of white moths on NP / # of NP moths on white / # of white moths on white / % of NP moths on NP / % of white moths on NP / % of NP moths on white / % of white moths on white

5. After you have recorded data for one trial using a white background and one trial using a newspaper background for each lab partner, compute the percentage of available prey recovered for the contrasting and matching background situations.

· To do this, divide the total number of discs recovered that contrasted with their background by the total number of disks of that type. Repeat this procedure with the total number of disks recovered that matched their background.

· For example, if you scatter 30 newspaper disks and 30 white disks on a sheet of newspaper, and you recover 5 newspaper (matching) disks and 15 white paper (contrasting) disks, your recovery rate is

5/30 x 100% = 17% for the matching background situation

15/30 x 100% = 50% for the contrasting background situation

· Record your computed percentages in the data table. Comparing percentages rather than raw numbers will give you a clearer picture of the effect or lack of effect that background contrast has on predation.

CLEAN-UP: Separate your disks and put them into the appropriate container. Put your forceps away and place the newspaper and white paper in the appropriate stack.

PART B:

TABLE A: Analyzing Predator-Prey Relationships

Year / Number of Light Moths Captured / Number of Dark Moths Captured
2 / 537 / 112
3 / 484 / 198
4 / 392 / 210
5 / 246 / 281
6 / 225 / 357
7 / 193 / 412
8 / 147 / 503
9 / 84 / 594
10 / 56 / 638

Table A represents data from a 10 year study of two varieties of the same species of peppered moths. The numbers represent moths captured in traps for 10 consecutive years. The traps were located in the same area each year.

1. Using the data provided in Table A (back page of lab), construct a graph in your lab notebook comparing the numbers of each variety of peppered moth. Label the axes with the years of the study (plotted horizontally) and the number of moths captured (plotted vertically). Use different colored pencils or a solid line and a dashed line to indicate the two color variations. Be sure to include a key beneath the graph

Analysis Questions – Use your graph, textbook or common knowledge, answer in your lab notebook, in complete sentences.

1. What preys on the peppered moth?

2. If the bark of trees is dark and the moths that rest there are light-colored, what will most likely happen to the moths?

3. What is a mutation?

4. What could have caused the first dark-colored moths to occur?

5. What caused the tree trunks of many trees in England to turn from a light color to a dark color?

6. Which variety of moth increased over the 10-year period?

7. What is the name of this type of evolutionary change? (Hint- read the 1st paragraph of the introduction)

8. Assume that you are selecting from a field of an equal number of light and dark “prey”. You would expect to pick up an approximately equal number of each type, if coloration is not important to predation success. What did your experiment indicate?

9. Using the data on the graph, draw a conclusion concerning the population of peppered moths in the sampled area of England.

10. Explain the reason for the increase in the number of dark colored moths.

11. What means could be used to return the environment of the peppered moth to its original state?

12. What effect would cleaning up the environment have on these moths?

Conclusion:

In your conclusion, restate the problem for the lab and summarize your procedure for how you completed the lab. Re-state your hypothesis and explain whether it was supported or refuted, why or why not. Develop a new questions that could be explored if the experiment was run again. Suggest experimental improvements or where errors may have occurred.