Download Natural Selection Lab Activity

Investigating Evolution
Purpose: In this activity, you will be simulating one mechanism for evolution that models the principles
of natural selection. Read through the lab handout to determine what the purpose of the lab is.
Pre-lab Preparation: In your lab book, complete the pre-lab. This includes a brief introduction, work
cited, the purpose (in your own words!), a hypothesis (if-then statement), a prediction for each habitat
type, procedure (flow chart format), and set up for results (all data tables are to be included and made
with a ruler).
Materials (per group): 1 plastic bag labeled “Beginning Population”
6 plastic bags (1 of each type of beans-brown pinto, white, red, black,
lentils, and yellow split peas), representing the prey
1 piece of fabric, representing the habitat
2 forceps
Procedure:
1. In your group, pick a “game warden”; the other three members will be the predators.
2. The game warden will pick up one bag containing the habitat (piece of fabric) and prey (bean
types) to use in this experiment. Also pick up 2 forceps for the predators to use.
3. Pick 20 beans from each bag and add them to the plastic bag labeled, “Beginning Population”.
Each type represents a different species. Record the total number of prey in your data table.
4. Lay flat the habitat in the center of your group.
5. The game warden will tell the predators to turn away from the habitat. The game warden will
then spread the prey in the “Beginning Population” across the habitat. He/she then tells the
predators to turn around and gather prey, ONE AT A TIME, using a forceps. The predators
must stop when the game warden says, “STOP” after 20 seconds.
6. After the hunting is stopped, students should determine how many prey are left in the habitat.
Count the number of each type of prey that the predators have captured. Subtract the number
of captured prey from the starting number; this is the number left in the habitat. The game
warden is responsible for recording these data in the data table 1.
7. To simulate reproduction among the prey, add 3 beans for each remaining bean of every type.
These beans, obtained from the bags containing extra beans, represent offspring. (surviving
number X 3 = offspring to be added to the environment)
8. Repeat the predation using the second generation of beans (Start # for Gen. 2 = survivors
from 1st generation plus new offspring). Again, record the number of remaining (surviving)
prey for the second generation.
9. Repeat the simulation of reproduction among the surviving prey as before. Instead of having
the predators hunt again, you may simply calculate the number of individuals that would be in
the third generation’s start population.
10. Share your data on the board, so that the class can get your data. Copy this data in tables 2a
and 2b. For each habitat, calculate the average number of surviving prey during each
generation. Record averages in data table 3a and 3b. [NOTE: Tables 3a and 3b are the tables
that will be included in your technical paper. However, as they are the only tables in your paper,
you will refer to them in your paper as table 1 and table 2.]
11. Re-sort the types of beans into the appropriate bags. Groups will lose 10% of their lab grade
for each bag that get mixed up!
Table 1: Group Data of Surviving Prey for each Generation in _________________ -colored
Habitat.
Number of prey for each generation
Species
1
2
3
Start #
Surviving Start # for Surviving
Start # for Gen. 3
for Gen. 1
#
Gen. 2
#
Black
20
Red
20
Pinto beans
20
Lentils
20
White
20
Yellow
20
Table 2a: Class Data of Prey for each Generation in Light-colored Habitat.
Surviving Number of prey for each generation
Species
1
2
Start # for Generation 3
Black
Red
Pinto
beans
Lentils
White
Yellow
Table 2b: Class Data of Prey for each Generation in Dark-colored Habitat.
Surviving Number of prey for each generation
Species
1
2
Start # for Generation 3
Black
Red
Pinto
beans
Lentils
White
Yellow
Table 3a: Average Number of Prey for each Generation in Light-colored Habitat.
Average Number of prey for each generation
Species
1
2
3
Surviving #
Surviving #
Start # for Gen. 3
Black
Red
Pinto beans
Lentils
White
Yellow
Table 3b: Average Number of Prey for each Generation in Dark-colored Habitat.
Average Number of prey for each generation
Species
1
2
3
Surviving #
Surviving #
Start # for Gen. 3
Black
Red
Pinto beans
Lentils
White
Yellow
12. For each habitat, use graph paper to construct a bar graph representing your data. You must
have one graph for each habitat. They should look similar to the following:
Axis labels
Number of prey
Chart heading
Number of prey surviving each generation in
light-colored habitat
red
40
purple
30
white
20
brown
10
blue
0
key
green
1
2
generation
3
yellow
Bar graph of data
for each generation
Post-lab preparation: Post-lab includes 2 graphs (see details above), the analysis questions
(questions and answers), and a well-written conclusion (see details below).
Analysis: Study the bar graphs of each generation. Answer the following questions.
1. Which, if any, types of prey survived better than others in the second- and third-generation
populations?
2. What might the reason be that predators did not select these types as much as they did other
types?
3. What effect did capturing a particular type of prey have on the numbers of that type in the
following generations?
4. Imagine a real-life predator-prey relationship and write a paragraph that describes how one or
more characteristics of the predator population or the prey population might change as a result
of natural selection.
Conclusion: Write a well-written conclusion that summarizes your understanding of biological
evolution as explained through natural selection. Restate your hypothesis. State if the hypothesis
was supported or not supported. Relate your results back to your hypothesis. Refer to the actual
results (class averages) and include analysis of the data in your explanation. Explain why the data
makes sense or not. Then explain possible errors groups may have made that could have affected
the class averages.