Natural Selection Goldfish Crackers lab
# ______ Name _____________________________________ Date ______________
Natural Selection Goldfish Crackers lab Introduction: Evolution is the change over time in the genetic makeup of a population. Natural selection is important in understanding this process, which is the basic idea that a population can change over generations if individuals that possess certain heritable traits leave more offspring than other individuals. Natural selection consists of four main steps: 1) Every species contains genetic variation, 2) Because organisms produce more offspring than can survive, living things face a constant struggle for existence, 3) Only some individuals survive and reproduce, and 4) Because each generation consists of the offspring of individuals that successfully reproduced, natural selection results in genetic change. These four steps of natural selection drive evolution. Understanding natural selection can be confusing and difficult. Although you have just learned that evolution works on populations over time and NOT on individuals, people often think that animals consciously adapt to their environments—that the peppered moth can change its color, the giraffe can permanently stretch its neck, the polar bear can turn itself white—all so that they can better survive in their environments. In this lab you will use goldfish crackers to help further your understanding of natural selection and evolution. Background: Facts about the fish 1. Although they look different, these fish all belong to the SAME species. 2. These little fish are the natural prey of the terrible carnivorous predators – YOU! 3. Fish come in two phenotypes—brown and gold. These two phenotypes are controlled by a gene with two different alleles: a. Brown: these fish taste bitter and are sneaky and hard to catch b. Gold: these fish taste yummy and are easy to catch 4. You, the terrible carnivorous predators, much prefer to eat the yummy gold fish; you eat ONLY gold fish unless none are available, in which case you resort to eating brown ones in order to stay alive. 5. New fish are born every year; the birth rate equals the death rate.
Your Data Table Generation
Gold
Brown
Total
1
10
2
10
3
10
4
10
5
10
Lab Group Data Table Generation
1 2 3 4 5
Gold
Brown
Total
Analysis: Complete a bar graph of the results of your lab. Each generation should have TWO different colored bars—one for the number of brown fish and one for the number of gold fish. Key
10 10
Brown Fish
99
Gold Fish
77 66
# # of of animals animals
Number of Fish
88
55 44
100 33 22
90
11 00
80
11
22
33
44
55
Generation Generation Generation
70 # of animals
Complete a bar graph of the results of your lab group. Each generation should have TWO different colored bars—one for the number of brown fish and one for the number of gold fish.
60
100
ofanimals animals ##of
Number of Fish
100
Key
90 90
50
Brown Fish
80 80
Gold Fish
70
40
70
60 60
30
50 50 40 40
20
30 20
10
10 10 0 0
0
1
1
1
2
2
2
3
3
3Generation 4 Generation Generation
Generation
4
5
4
5
5
Copy the results of the class into the table below .
Class Data Table Generation
Gold
Brown
Total
1 2 3 4 5 Complete a bar graph of the results of the class. Each generation should have TWO different colored bars—one for the number of brown fish and one for the number of gold fish. 100 100
Key
90 90
Brown Fish
80 80
Gold Fish
70 # of animals
Number of Fish # of animals
70
60 60
50 50 40 40 30 20 10 10 0 0 1
1
2
2
3
3
Generation
Generation Generation
4
4
5
5
Analyze: 1. According to the bar graphs, what happens to the allele frequencies (number of the brown and gold alleles) from generation 1 to generation 5?
2. Explain which phenotype (color) is NOT favorable to the animals and why.
3. What process is occurring when there is a change in the genetic makeup of a population over a long period of time?
4. If you were to repeat this same experiment but with a blindfold so that you could not see which color fish cracker you were eating, would you expect a certain color to become more common over generations? HINT: If the predators of the fish crackers could only find fish by touch, would it be better for the fish cracker (prey) to be one color or the other?
5. What do you think would have happened in this experiment if you continued for 10 more generations?
6. What did you learn from this experiment?
Natural Selection Goldfish Crackers lab Teacher’s Notes 1.) Need two types of goldfish crackers. Brown and Gold. 2.) Split the class into groups. 3.) R ead first page together as a whole class. Discuss. 4.) For Generation 1 – Pass out 10 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 5.) For Generation 2 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 6.) For Generation 3 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 7.) For Generation 4 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 8.) For Generation 5 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. 9.) Students now work with their group or individually to graph the results and analyze the results.
Natural Selection Goldfish Crackers lab Introduction: Evolution is the change over time in the genetic makeup of a population. Natural selection is important in understanding this process, which is the basic idea that a population can change over generations if individuals that possess certain heritable traits leave more offspring than other individuals. Natural selection consists of four main steps: 1) Every species contains genetic variation, 2) Because organisms produce more offspring than can survive, living things face a constant struggle for existence, 3) Only some individuals survive and reproduce, and 4) Because each generation consists of the offspring of individuals that successfully reproduced, natural selection results in genetic change. These four steps of natural selection drive evolution. Understanding natural selection can be confusing and difficult. Although you have just learned that evolution works on populations over time and NOT on individuals, people often think that animals consciously adapt to their environments—that the peppered moth can change its color, the giraffe can permanently stretch its neck, the polar bear can turn itself white—all so that they can better survive in their environments. In this lab you will use goldfish crackers to help further your understanding of natural selection and evolution. Background: Facts about the fish 1. Although they look different, these fish all belong to the SAME species. 2. These little fish are the natural prey of the terrible carnivorous predators – YOU! 3. Fish come in two phenotypes—brown and gold. These two phenotypes are controlled by a gene with two different alleles: a. Brown: these fish taste bitter and are sneaky and hard to catch b. Gold: these fish taste yummy and are easy to catch 4. You, the terrible carnivorous predators, much prefer to eat the yummy gold fish; you eat ONLY gold fish unless none are available, in which case you resort to eating brown ones in order to stay alive. 5. New fish are born every year; the birth rate equals the death rate.
Your Data Table Generation
Gold
Brown
Total
1
10
2
10
3
10
4
10
5
10
Lab Group Data Table Generation
1 2 3 4 5
Gold
Brown
Total
Analysis: Complete a bar graph of the results of your lab. Each generation should have TWO different colored bars—one for the number of brown fish and one for the number of gold fish. Key
10 10
Brown Fish
99
Gold Fish
77 66
# # of of animals animals
Number of Fish
88
55 44
100 33 22
90
11 00
80
11
22
33
44
55
Generation Generation Generation
70 # of animals
Complete a bar graph of the results of your lab group. Each generation should have TWO different colored bars—one for the number of brown fish and one for the number of gold fish.
60
100
ofanimals animals ##of
Number of Fish
100
Key
90 90
50
Brown Fish
80 80
Gold Fish
70
40
70
60 60
30
50 50 40 40
20
30 20
10
10 10 0 0
0
1
1
1
2
2
2
3
3
3Generation 4 Generation Generation
Generation
4
5
4
5
5
Copy the results of the class into the table below .
Class Data Table Generation
Gold
Brown
Total
1 2 3 4 5 Complete a bar graph of the results of the class. Each generation should have TWO different colored bars—one for the number of brown fish and one for the number of gold fish. 100 100
Key
90 90
Brown Fish
80 80
Gold Fish
70 # of animals
Number of Fish # of animals
70
60 60
50 50 40 40 30 20 10 10 0 0 1
1
2
2
3
3
Generation
Generation Generation
4
4
5
5
Analyze: 1. According to the bar graphs, what happens to the allele frequencies (number of the brown and gold alleles) from generation 1 to generation 5?
2. Explain which phenotype (color) is NOT favorable to the animals and why.
3. What process is occurring when there is a change in the genetic makeup of a population over a long period of time?
4. If you were to repeat this same experiment but with a blindfold so that you could not see which color fish cracker you were eating, would you expect a certain color to become more common over generations? HINT: If the predators of the fish crackers could only find fish by touch, would it be better for the fish cracker (prey) to be one color or the other?
5. What do you think would have happened in this experiment if you continued for 10 more generations?
6. What did you learn from this experiment?
Natural Selection Goldfish Crackers lab Teacher’s Notes 1.) Need two types of goldfish crackers. Brown and Gold. 2.) Split the class into groups. 3.) R ead first page together as a whole class. Discuss. 4.) For Generation 1 – Pass out 10 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 5.) For Generation 2 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 6.) For Generation 3 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 7.) For Generation 4 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. Then the group fills in the number of each color in the group data table. Students eat 4 goldfish; unless there are none then they eat brown. (no more than 4) 8.) For Generation 5 – Pass out 4 goldfish crackers randomly to each student. They then log in their data table number of each color. 9.) Students now work with their group or individually to graph the results and analyze the results.
