Student Exploration: Natural Selection

Student Exploration: Natural Selection

Vocabulary: biological evolution, camouflage, Industrial Revolution, lichen, morph, natural selection, peppered moth

Prior Knowledge Questions (Do these BEFORE using the Gizmo.)

Student Exploration: Natural Selection Gizmo Warm-up

The Natural Selection Gizmo™ allows you to play the role of a bird feeding on peppered moths. The initial population of 40 moths is scattered over 20 tree trunks. Click on moths to capture them. Click the Next tree button (or the spacebar on your keyboard) to advance to the next tree.

Check that LIGHT TREES is selected. Click Play (), and hunt moths for one year.

How many dark moths did you capture? _______

How many light moths did you capture? _______

Camouflage is coloring or patterns that help an organism to blend in with the background. Which type of moth is better camouflaged on light bark? ____________

If a forest contained mostly light-colored trees, which type of moth would you expect to be most common? ____________________________________________________________

Activity A:

Light trees

Get the Gizmo ready:

· Click Reset ().

· Check that the LIGHT TREES tab is selected.

Introduction: Before the 19^th century in England, the air was very clean. The bark on trees was usually light in color. Abundant lichens growing on tree trunks also lightened their appearance.

Student Exploration: Natural Selection Question 1:

How does the color of a peppered moth affect survival?

Predict: Over time, what will to happen to the populations of light and dark moths on light trees? ____________________________________________________________________

Experiment: Click Play and hunt peppered moths on light tree trunks for five years. In each year, try to capture as many moths as you can. Note: You can use the spacebar on your keyboard to quickly advance to the next tree.

After 5 years, select the TABLE tab and record the percentages of each moth type. (Note: The table shows current populations of each moth, not the number of captured moths. You don’t have to Export the table.)

Year	Dark moths	Light moths
0
1
2
3
4
5

Then click the GRAPH tab, click the camera icon on the upper right to take a snapshot of the graph of your 5 year totals. Paste the snapshot into the lab report in the space below:

Picture of Graph:

Analyze: What do your results show? ___________________________________________

_________________________________________________________________________

Apply: Which type of moth do you think was more common before the 19^th century, when most trees were light in color? _________________________________________________

Extend your thinking: What strategies did you use to hunt for moths? __________________

_________________________________________________________________________

Activity B:

Dark trees

Get the Gizmo ready:

· Click Reset.

· Select the DARK TREES tab.

Introduction: The 19^th century was the time of the Industrial Revolution in England. Most of the new industries used coal for energy, and the air was polluted with black soot. In forests near factories, the soot coated trees and killed lichens. As a result, tree trunks became darker.

Student Exploration: Natural Selection Question 2:

How did air pollution affect moth populations?

Predict: Over time, what will to happen to the populations of light and dark moths on dark trees? ____________________________________________________________________

Experiment: Click Play and hunt peppered moths on dark tree trunks for five years. In each year, try to capture as many moths as you can.

When you are done, select the TABLE tab and record the percentages of each moth type.

Year	Dark moths	Light moths
0
1
2
3
4
5

Then click the GRAPH tab, click the camera icon on the upper right to take a snapshot of the graph of your 5 year totals. Paste the snapshot into the lab report in the space below:

Picture of Graph:

Analyze: What do your results show? ___________________________________________

_________________________________________________________________________

Apply: Which type of moth do you think was more common during the 19^th century? Why?

_________________________________________________________________________

(Activity B continued on next page)

Activity B (continued from previous page)

Draw conclusions: Natural selection is the process by which favorable traits tend to increase in frequency over time. How does this experiment illustrate natural selection?

_________________________________________________________________________

Think and discuss: Did the changes you observed in the moth populations result from individual moths changing colors? Or did they occur because the best-hidden moths survived and reproduced, passing on their colors to their offspring? Explain your answer.

_________________________________________________________________________

Extend your thinking: Biological evolution is the process by which populations of organisms change over time. How could natural selection lead to evolution? If possible, discuss your answer with your classmates and teacher.

_________________________________________________________________________

Student Exploration: Natural Selection

Online biology exam

Last Updated on March 26, 2019