Lab 1: Natural Selection

Natural Selection Lab Activity

Introduction

In his book, On the Origin of Species, Charles Darwin described the idea of natural selection as a fundamental mechanism of change. Natural selection is the idea that modifications to a species, which are beneficial to the species, allow it to survive. Those modifications that place the species at a disadvantage will die off. Darwin used the following five considerations when arriving at his definition of natural selection.
1. All species are engaged in a struggle to survive in their environment.
2. Environmental conditions change over time.
3. Species change through continual modifications.
4. Modifications that are best suited for the environment are preserved.
5. Evolutionary change is result of the natural selection of successful modifications

Lab Activity

In this lab activity,
1. You will study how a predator exerts a selective force on the survival of its prey in a
given environment.
2. You will also theorize on the variation of a prey species that determines which
individuals in the species are more likely to fall prey to a predator.
3. You will consider how the environment and the prey affect the success of the predator.


Materials
1000 lentils 1000 navy beans knife chopsticks
1000 garbonzo beans 4 cups fork stopwatch
1000 butter beans carpeting spoon


Procedure
Part A
1. Get into groups of 5
2. Choose 1 person to be timer/referee/recorder.
3. The other 4 “predators” choose a utensil and a cup
4. Scatter the seeds about the carpeting or assigned space.

**Predictions**
1. What variation of the prey species (seeds) is likely to be the most successful at survival? Why?


2. What variation of the prey species (seeds) is likely to be the least successful at survival? Why?


3. What predator species (utensils) is likely to be the most successful at gathering prey? Why?


4. What predator species (utensils) is likely to be the least successful at gathering prey? Why?
5. Students (predators) will forage for their prey according to the following
a. seeds must be picked up by utensils only
b. seeds must be picked up one at a time and placed in a cup
c. each utensil wielding predator must count the number of each type of seed at the end
of each foraging session
6. Set the stopwatch for 3 minutes and begin foraging.
7. At the end of 3 minutes count how many seeds of each type are present and record in Table A.

Table A
First Generation
Prey Captured Lentils Garbanzos Navy Butter Total Captured
by Predator Prey
Knife
Fork
Spoon
Chopsticks
Total Captured

8. Determine predator efficiency by determining how much time each predator will be allowed
to forage in the second generation.

B= total prey caught by a single predator
Bt=total prey captured by all predators
S= number of seconds of foraging time for the predator in that round

forage time = B x S
in next round Bt

9. Enter the foraging time for each predator in Table B.

Part B
1. Using the forage time determined from #9 above, allow each predator to forage for the exact
amount of time as recorded in table 2.
2. Record results in Table B below
Table B
Second Generation
Predator Lentils Garbanzos Navy Butter Total Captured
Foraging Time Prey
Knife____________
Fork____________
Spoon___________
Chopsticks________
Total Captured

3. Calculate the foraging time for the third generation and record in Table C.




Part C
1. Using the forage time determined from Part B #3 above, allow each predator to forage for the
exact amount of time as recorded in Table C.
2. Record foraging results for the third generation in Table C below.

Table C
Third Generation
Predator Lentils Garbanzos Navy Butter Total Captured
Foraging Time Prey
Knife____________
Fork____________
Spoon___________
Chopsticks________
Total Captured

3. Calculate the foraging time for the fourth generation and record in Table D.

Part D
1. Using the forage time determined from Part C #3 above, allow each predator to forage for the
exact amount of time as recorded in Table D.
2. Record foraging results for the fourth generation in Table D below.

Table D
Fourth Generation
Predator Lentils Garbanzos Navy Butter Total Captured
Foraging Time Prey
Knife____________
Fork____________
Spoon___________
Chopsticks________
Total Captured

Part E. Questions

1. Which predator was most successful in obtaining prey? Why?



2. Which prey was most successful at avoiding capture? Why?



3. Which predator was the least successful in obtaining prey? Why?



4. Which prey was the least successful at survival? Why?


5. What does the steady reduction in foraging time represent?




6. Were your predictions correct about which type of predator and prey would be most and least
successful? Explain why you predicted the way you did.



7. What happens to the types of prey over time?




8. What happens to the types of predators over time?




9. Go around to other groups and see if different environments made a difference in the survival
rates of different prey. Record the most and least successful predator and prey for the different
environments below.

Most Successful Least Successful Most Successful Least Successful
10. Environment Predator Predator Prey Prey












11. Describe the advantage or disadvantage an environment gave the predators.







12. Describe the advantage or disadvantage an environment gave the prey.