Peppered Moth Simulation
Objective:
Simulate changes in moth population due to pollution and predation, and observe how species can change over time.
Introduction:
The following information is from the site: http://www.biologycorner.com/worksheets/pepperedmoth.html
Charles Darwin accumulated a tremendous collection of facts to support the theory of evolution by natural selection. One of his difficulties in demonstrating the theory, however, was the lack of an example of evolution over a short period of time, which could be observed as it was taking place in nature. Although Darwin was unaware of it, remarkable examples of evolution, which might have helped to persuade people of his theory, were in the countryside of his native England. One such example is the evolution of the peppered moth Biston betularia.
The economic changes known as the industrial revolution began in the middle of the eighteenth century. Since then, tons of soot has been deposited on the country side around industrial areas. The soot discolored and generally darkened the surfaces of trees and rocks. In 1848, a dark-colored moth was first recorded. Today, in some areas, 90% or more of the-peppered moths are dark in color. More than 70 species of moth in England have undergone a change from light to dark. Similar observations have been made in other industrial nations, including the United States.
Industrial Melanism is a term used to describe the adaptation of a population in response to pollution. One example of rapid industrial melanism occurred in populations of peppered moths in the area of Manchester, England from 1845 to 1890. Before the industrial revolution, the trunks of the trees in the forest around Manchester were light grayish-green due to the presence of lichens. Most of the peppered moths in the area were light colored with dark spots. As the industrial revolution progressed, the tree trunks became covered with soot and turned dark. Over a period of 45 years, the dark variety of the peppered moth became more common.
Use the information above and Wikipedia to answer the following pre lab questions. Copy the questions to a word document and answer. Next, print out the page and have your teacher initial it before continuing.
- What is natural selection?
- Who is Darwin?
- In your own words explain Darwin’s theory of evolution.
- What environmental problem was caused by the industrial revolution?
- What is the difference between the lichen forest and the sooty forest?
- What is the purpose of this lab?
****You must have this paper initialed by your teacher before you can move on to the experiment.
Lab Instructions:
Go to the following web site: http://www.biologycorner.com/worksheets/pepperedmoth.html
You will run two simulations for 5 minutes each (use the timer at the top of the webpage). During this time you will play the part of a blue jay that eats moths. It is important that your blue jay's health does not fall below 50%. After 5 minutes record below the % of dark moths and light moths. This is important! You will need this information later!
Observations & Analysis:
Data Table - Create this table in Excel and then copy the questions below into you word document and answer them.
| Percent Dark Moths | Percent Light Moths | |
| Lichen Forest | ||
| Sooty Forest |
- What did the experiment show about how prey is selected by predators?
- What moth coloration is the best adaptation for a sooty forest? How do you know?
- What would you expect the next generation of moths to look like after running the simulation for 10 minutes? What about the next generation after 20 minutes?
- How does the simulation model natural selection?
- Explain how the color of moths increases or decreases their chances of survival depending on the environment.
- 500 light colored moths and 500 dark colored moths are released into a polluted forest. After 2 days the moths were recaptured, make a prediction about the number of each type of moth that would be captured.
- How has the strong change in coloration come about? (Include an explanation of how the dark moth appeared and how the proportion of dark moths changed from 0.0005% to more than 90% in polluted forests.)
- What underlying law of nature has produced this change? (Use Darwin's theory of evolution and apply it to what you have learned in this investigation.)
Now put the following data into an Excel worksheet. Use the following table to construct a line graph in Excel. Your graph should look like the graph at the top of this page if you've done it correctly.
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 |
337 |
7 |
193 |
412 |
8 |
147 |
503 |
9 |
84 |
550 |
10 |
56 |
559 |
Copy these next two questions on to your word document and use the graph you constructed to help answer them.
- Explain in your own words what the graph shows.
- Describe a situation where this type of selection might occur.
- What is a model?
- Why do scientists use models?
- All models have limitations because they are a simplified version of the real world. What are some limitations of this peppermoth model? Be very specific. You will need to come up with at least 3 limitations.
All of the information on this page was adapted from the worksheet found here http://www.biologycorner.com/worksheets/pepperedmoth.html
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