Natural Selection

Natural selection is the evolutionary process by which the most adaptable individuals in a particular environment survive. When the organism survives, it is more likely to reproduce and pass on its inherited traits. Many organisms are best adapted for their environment because they have inherited the ability to camouflage themselves. A predator organism can avoid being seen by its prey, or a prey organism can avoid being seen by its predator.

Pre-lab work: www.howstuffworks.com/animal-camouflage.htm

Read the article and answer the following questions.

1. What are 2 possible common organisms that the Paradoxophyla palmata may be hiding from and explain why?

2. What is the most important factor that determines what camouflage will look like? How does the tartan hawkfish illustrate this factor?

3. Why does the artic fox change the color of its fur?

4. State the 2 ways a zebra hides from a lion?

5. What is the advantage of camouflage over “weapons of defense”?

Prior to administering this lab:

1. Buy a New York Times and save the sheets that are only black and white.

2. Save enough newspapers to use as territories.

3. Cut up enough 1cm newspaper squares so that each group of 4 will have 50.

4. Do the same with construction paper.

Experimental Design

1. Assign each group member a number from 1-4 (or less in smaller groups).

2. Place the newspaper (territory) flat on the desk so that all group members

(predators) are able to reach it.

3. Count out 50 newspaper squares (prey organisms) and 50 colored squares (prey

organisms).

4. Place all squares on the newspaper randomly (the squares should not overlap)

and face away from the newspaper.

5. When every group is ready, the teacher will begin calling out numbers. When your

number is called, quickly turn around and grab the first square you see and then

look away.

Hypothesis

(Which squares will more likely be picked by you and your classmates?)

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Give a reason for your hypothesis.

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Data

Student Names	Newspaper Squares Picked	Colored Squares Picked
1
2
3
4
Total number of squares picked

Class Data (for the board)

Group Number	Total Newspaper Squares Picked	Total Colored Squares Picked
1
2
3
4
5
6
7
8

Analysis and Conclusion

1. Not all of your classmates picked to same number of each type of square. Offer some possible explanations.

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2. Do the results agree/disagree with your hypothesis? Explain using specific examples from your data.

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3. If the squares are reproducible organisms that passed on their color trait to their offspring, predict what would happen to the number of newspaper organisms and colored organisms with each passing generation.

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4. Examine the table, which represent data from a 10-year study of a population of peppered moths. The numbers represent moths captured in traps that were located in the same area each year.

Year	Number of light captured moths	Number of dark captured moths
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

Create a line graph from this data. Hint: The year is the independent variable. Make a key for the two different types of captured moths.

5. Describe the trend in population (size of population relative to year) for each type of peppered moths.

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6. These moths inhabit trees that have been darkened by industrial pollution. Give a possible explanation for their current population trend.

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7. If this environment is cleaned up, predict what might happen to the number of each type of moth.

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National Science Standards:

Life Science Standard 6.3 Biological Evolution and Interdependence of organisms.