1. Activity 95: Hiding in the Background
Challenge How do factors such as the environment and the presence of predators affect the process of natural selection?
Key Vocabulary:
Natural Selection – (see definition in Act. #94)
Camouflage
color, texture, patterning, or shape that allow an organism to blend in with it’s surroundings.
Glue in SS95.1 & Open to Pg. 30

2. Examples of Camouflage:
Look at the following pictures….Can you find the animal??

11. Photo by Theuerkauf

12. What does Camouflage have to do with Evolution?

13. Adaptive Coloration & The Peppered Moth
Example:
Adaptive Coloration & The Peppered Moth
First record of a black moth was in 1848
Both the black moth and white moths coexisted.
By 1895, 98% of the populations in that area were dark
Blamed on the Industrial revolution which covered tree trunks with soot

14. Getting Started with Activity 95
Imagine a population of worms in which there is some variation in color.
Some worms are lighter and some are darker.
Birds eat these worms. Most of the birds that eat these worms are better at seeing lighter worms.
Which worms do you think are more likely to be eaten?
What do you think would happen
to the color of the worm
population over many years? Why?

15. Procedure – page 31 There must always be 50 worms in the grass.
Each student “eats” 10 worms per generation.
Count your worms and record the number of green and beige on your “personal worm count chart”
Add your groups’ number of green and beige and record it on the table.
Add the number of “offspring” found in Row #4 before beginning the next generation.

16. Analysis Answers #1-6

17. These will be different for each group’s data
Analysis #1
Generation 1: 25:25 Generation 2: _________ Generation 3: _________
Because we had a beige background, the number of beige worms should increase. The number of green worms should decrease.
These will be different for each group’s data

18. This is Natural Selection!
Write it Down!!
#1 Continued
The worms that we camouflaged were harder to see allowing them to survive and reproduce more. This increased their overall population. The worms that are easier to see were “eaten” so they did not have as many offspring and their populations decreased.

19. #2
The trend should continue, with the number of beige worms increasing. The green worms may disappear altogether, leading to a ratio of 50:0

20. This is Natural Selection!#3
If the background turns green…
Green worms are now better suited to their environment!
Green worms are more likely to survive and reproduce.
Therefore, the green worm population would increase while the beige worm would be expected to decrease.
This is Natural Selection!
Write it Down!!

21. #4
The color of the environment determined which type of worm was more likely to be eaten by a predator Only the worms that survived to reproduce could pass on their color trait to their offspring.
The vision of the predator relied on the contrast between the color of the worm and the color of the background surface. The predator does not “choose” or “decide” which color worm is easier to see, but just preys upon the worms.

22. #5 Strengths Weaknesses
Animals that blend in are more likely to survive
Only worms that survived could reproduce
The percentage of worms of each color changed over time
Didn’t have to search very hard to find worms
Not all worms would reproduce at the steady rate we used; other factors could affect the population
The worms didn’t totally blend in to the background

23. #6
Earthworms , presumably have camouflage that has evolved relative to the color of the soil ( or foliage that is dried out or is normally beige or brown), rather than the color of the green grass.