answer the following questions: "Science 10								
Mechanisms of Evolution Activity
You will be investigating 3 different mechanisms of evolution. Natural selection, gene flow, and genetic drift are processes that lead to genetic changes in populations. After finishing these activities, you will be able to compare and analyze the effect of each of these mechanisms on the populations.  
Activity One: Evolution via Natural Selection 
In this simulation, you will model the effect of a predator (you) on the evolution of an insect population (toothpicks). This species of insect has 5 color variations: red, blue, green, yellow, and tan. You will “eat” the insects and record data. Work with a partner, and decide who Partner A is and who Partner B is before beginning. 
You should begin with:  
-Plastic bag: the “stomach” of the predator 
-8 toothpicks of each color (40 total): the “insects” 
1) Find an area outside (about 10ft x 10ft) that’s away from other groups. It should be in grass, dirt, or leaves. 
2) Partner A randomly scatters all 40 of the toothpicks around the area without Partner B  looking. 
3) Partner B is now the first predator! Collect the first 20 toothpicks you see and place  them in the plastic bag. Make sure to look away from the ground after each toothpick is picked up. Partner A should help count the toothpicks to make sure exactly 20 are  collected. 
4) Count how many toothpicks of each color were collected and record it in your data  table. Calculate how many toothpicks of each color are remaining in the habitat. 
5) The insects reproduce! Each surviving insect in the habitat will produce one offspring.  For each toothpick that is remaining in the habitat, add one new toothpick of the same color to the habitat. Record this in your data table. Partner B should scatter the  offspring into the habitat while Partner A isn’t looking. (Example: If 5 blue toothpicks  remain in the habitat, add 5 new blue toothpicks to the habitat, and record 10 total  remaining after reproduction in the data table) 
6) Partner A is now the predator for Generation 2. Collect exactly 20 more toothpicks from the habitat while Partner B helps count. 
7) Repeat steps 4 and 5 in which you record data and add offspring to the habitat. 
8) Partner B is now the predator again for Generation 3. Collect 20 toothpicks and record the data as you did for the previous generations. 
9) Do not put any more toothpicks into the habitat. Clean up the toothpicks still remaining in the habitat and return them to containers. 
Generation 1 
COLOR 
# IN HABITAT 
# COLLECTED 
# REMAINING 
TOTAL #  
REMAINING AFTER  REPRODUCTION
Red 
8
4
4
8
Yellow 
8
3
5
10
Blue 
8
5
3
6
Green 
8
4
4
8
Tan 
8
4
4
8
TOTAL 
40
20
20
40



Generation 2
COLOR 
# IN HABITAT 
# COLLECTED 
# REMAINING 
TOTAL #  
REMAINING AFTER  REPRODUCTION
Red
8
3
5
10
Yellow
10
5
5
10
Blue
6
4
2
4
Green
8
1
7
14
Tan
8
7
1
2
TOTAL
40
20
20
40






Generation 3 
COLOR 
# IN HABITAT 
# COLLECTED 
# REMAINING 
TOTAL #  
REMAINING AFTER  REPRODUCTION
Red
10
7
3
6
Yellow
10
5
5
10
Blue
4
4
0
0
Green
14
4
10
20
Tan
2
0
2
4
TOTAL
40
20
20
40



1. Describe a real example of natural selection. 


When brown moths live at higher rates than other colored moths because the brown ones can blend in with the TREES


2. Does your data suggest that a certain color of toothpick is advantageous? Which color?


It suggests that green color is advantageous


3. Why might some colors/phenotypes survive better than others in this particular habitat? 

Green will survive at higher rates because the grass is green (camouflage) 🤯



4. How might the results be different if this activity was performed in a habitat that is  mostly red?
Then the red sticks would survive at similar rates as the green ones did
5. What is an adaptation as it relates to natural selection? 
An adaptation is a trait that changes within an organism and often an entire species that assists it in increasing its odds of survival and in turn, reproduction
5. Graph the total number of each color remaining after reproduction after the third generation. Make sure to label the axes of the graph and title it. 












Activity Two: Evolution via Genetic Drift 
You should begin with:  
-8 toothpicks of each color (40 total): the “insects” 
-Plastic bag: the “environment” 
1) Place all 40 toothpicks in the plastic bag. 
2) Disaster strikes the habitat! An event such as a fire, flood, or meteor strike causes half of the population to die. Partner A closes their eyes and removes 20 toothpicks from the bag at random. Partner B should help count. 
3) The remaining toothpicks will reproduce by adding one new toothpick of the same color  to the bag for each toothpick remaining in the bag after the disaster. Record this in your data table. 
4) Reset the experiment and run 2 more trials. This means you should begin each trial with 8 toothpicks of each color and perform 3 separate trials total.
Trial 1 
COLOR 
STARTING  
POPULATION
# AFTER EVENT 
# AFTER  
REPRODUCTION
Red 
8
4
8
Yellow 
8
2
4
Blue 
8
3
6
Green 
8
4
8
Tan 
8
7
14
TOTAL 
40
20
40


Trial 2 
COLOR 
STARTING  
POPULATION
# AFTER EVENT 
# AFTER  
REPRODUCTION
Red 
8
2
4
Yellow 
8
4
8
Blue 
8
4
8
Green 
8
5
10
Tan 
8
5
10
TOTAL 
40
20
40


Trial 3
COLOR 
STARTING  
POPULATION
# AFTER EVENT 
# AFTER  
REPRODUCTION
Red 
8
4
8
Yellow 
8
4
8
Blue 
8
4
8
Green 
8
5
10
Tan 
8
3
6
TOTAL 
40
20
40


1. Describe a real example of genetic drift. 

2. Define evolutionary fitness. Is this mechanism based on an organism’s fitness or is it random? 
Evolutionary fitness is how well a species is able to survive in its environment, and it is based on an organisms fitness 
3. Did genetic variation within the population increase or decrease? Why? 


4. How might the end result be different if originally… 
a) 10 individuals were removed?  
b) 30 individuals were removed?
5. Choose just one of your trials and graph the amount of each color toothpick after reproduction. Make sure to label the axes of the graph and title it.

Insert graph here


Activity Three: Evolution via Gene Flow 
You should begin with: 
-20 toothpicks each of 2 different colors (40 total): the “insects” 
-Plastic bag: the “environment” 

1) Record the starting number of toothpicks of each color in your data table. 
2) Some insects start to leave your population, and some new ones are moving in! Your  population will exchange individual organisms with a different population. Partner B  closes their eyes and removes 4 toothpicks from your bag at random.  
3) Give your 4 toothpicks to a different group, and collect 4 toothpicks from the other group. Add the 4 toothpicks they gave you to your bag. You should still have 40  toothpicks total at the end of each generation. 
4) Count the number of each color toothpick you have in your bag and record your results. 
5) The insects keep moving! Trade with 3 more groups, counting and recording your data  at each generation. After you have exchanged toothpicks 4 times total, you should still  have 40 toothpicks total.
Gene Flow 
COLOR 
STARTING  
POPULATION
GENERATION  2
GENERATION  3
GENERATION  4
GENERATION  5
Red
0
0
1
3
2
Yellow
20
18
20
17
17
Blue
0
3
3
5
7
Green
0
0
0
0
2
Tan
20
19
16
15
12
TOTAL 
40 
40 
40 
40 
40



1. Describe a real example of gene flow.  

An example of this is pollen being blown to a new destination or people moving to new cities or countries.

2. How many colors did you begin with, and how many were present at the end of the  5th generation? 
3. Why is genetic variation important in a population? 
4. How does this process lead to changes in gene frequencies in the population as the  mechanism occurs?


5. Graph the amount of each color remaining at the end of the 5th generation. Make  sure to label the axes and title the graph.
Insert graph here
Resources:
Chapter#11: Evolution (Science 10 Reader)
Mechanisms: the processes of evolut
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