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Name N A T U R A L S E L E C T I O N BACKGROUND/INTRODUCTION In all our talks of NATURAL SELECTION, we have always said that it take millions of years for a species to show any kind of change. While this is true for the most part, there are circumstances that allow us to see evolution happening on a much quicker scale. In the 19th century, England was going through an industrial revolution. During this time period the country saw a great increase in coal burning due to the many factories that were in business. When coal is burned, soot is produced. This soot began to coat the trees and buildings that were near the city. The bark on the birch trees, in those areas, were blackened by the soot. Before this time period the peppered moths in this area were mostly lightly colored. This allowed them to be camouflaged against the white birch trees from their natural predators, birds. During this industrial revolution, a dark form of the moth became more and more common. Since this shift in pigmentation was caused by industry, the rise of these dark colored moths came to be known as INDUSTRIAL MELANISM (the pigment in moths that gives them this coloration is called melanin). In this lab, you will be the moths’ natural predator, a bird, and we will see why these conditions caused such a rapid change in this species of moth. *****READ THE WHOLE PROCEDURE FIRST, THEN BEGIN***** PROCEDURE: 1. You will obtain a background (either light, medium, or dark), and an envelope of light moths and envelope of dark moths. 2. One person is the predator and this person should turn their back so they cannot see the background. Meanwhile, the other person, the recorder, will lay 5 light and 5 dark moths randomly on that background. 3. When ready, the recorder will tell the predator to turn around and the predator will have 5 seconds to remove/pick up as many moths as possible. YOU CAN ONLY REMOVE ONE MOTH AT A TIME AND YOU MUST USE YOUR THUMB AND FOREFINGER TO REMOVE THEM. 4. After the 5 seconds, count the “survivors” left on the background and record in Generation 1 in Table 1. 5. All survivors now have the ability to reproduce. Therefore, for every surviving moth, add one more to the background. Basically, double the survivors. 6. Again, the predator should turn their back and recorder scatters moths randomly then allows 5 seconds for predation. Record results as generation 2. 7. Once doubling the survivors, just like before, obtain data for generation 3. 8. Then complete Table 2 by using your information, then find groups that had different backgrounds than your own to complete Table 2. GRAPHING: Make a LINE graph comparing the percentage of dark moths over the 3 trials/generations. You should have 3 lines (one for each background). Use different color pens/markers and make a key. You are graphing the generation/trial against the percentage change. YOUR GRAPH MUST USE AT LEAST HALF OF THE GRAPH PAPER AND YOU MUST FOLLOW ALL GRAPHING RULES. ANALYSIS QUESTIONS: 1. Using your data in Table 2, compare the 3 backgrounds. What trends did you observe from Generation 1 to Generation 3 for the : Light Background: Medium Background: Dark Background: 2. Let’s say that we went out to 4 generations in this activity. Make a prediction (using actual numbers) as to what you expect to see if we actually completed Generation 4 for the light moths and the dark moths. Predicted # of light moths for Generation 4 = _____ Predicted # of dark moths for Generation 4 = _____ 3. Explain, in terms of evolution, why you received the results that you did. Use appropriate terminology. 4. Given that today, there are more air pollution laws, what do you think is occurring with the number of light moths and number of dark moths in England? 5. As a preview of what is coming up in our studies, what type of natural selection does the peppered moth example demonstrate….directional, stabilizing, or disruptive? Read (in Chapter 16) and research if necessary. Table 1: Color of the Background ___________________________ # of Light Moths # of Dark Moths Original Population Generation 1 Survivors Generation 2 Survivors Generation 3 Survivors Table 2: Group Data Background Color Light Medium Dark % of Dark in Generation 1 % of Dark in Generation 2 % of Dark in Generation 3