Name: _______________________
Biology Evolution Formal Lab
http://www.mhhe.com/biosci/genbio/virtual_labs/BL_12/BL_12.html.
Purpose: To investigate how natural selection affects allelic frequencies.
To investigate a simulated model of natural selection of an organism in
different environments.
Background Information:
A predator finds certain phenotypes of prey more easily in environments in
which the prey do not blend in. By placing pressure (predator, change in
environments, etc.) on specific phenotypes, a change in the frequency of
the alleles that produce these phenotypes will occur. Natural selection can
significantly alter the genetic equilibrium of a population’s gene pool over
time. Evolution can be described as the change in allelic frequencies of a
gene pool over time. This can lead to the evolution of a new species.
For this lab, the organisms’ survival will depend upon a single gene with
two alleles, A and a, that show incomplete dominance. These alleles
combine to form three genotypes and three phenotypes as outlined in the
chart below:
GENOTYPE
AA
Aa
aa
Materials:
1 Laptop
Lab Handout
Pen or pencil
Graph paper
PHENOTYPE (Color)
Yellow
Brown
Grey
Procedure:
1. Select the Initial Allelic Frequencies of A and a and an
environment. The number of organisms of each genotype will be
displayed on the screen. Record the numbers in the data table
below.
2. Click the Natural Selection Button to show the number of organisms
of each genotype that survive after natural selection has taken place.
The display will also show how natural selection has affected allelic
frequencies.
3. Click a Generation Button, in order, from G1 through G5, to display
100 organisms in the proportions representing the new allelic
frequencies after natural selection has occurred in the previous
generation.
4. Collect and record data on allelic frequency changes due to natural
selection in the population over five generations.
5. Use the Reset Button to collect data with different initial allele
frequencies or different environments.
6. Repeat the simulation using a different Environment.
Design Set-Up: Draw or take a picture of the organisms and their habitat
as they appear on the screen and label all components.
Trial 1:
Environment: ____________________________
Hypothesis: The phenotype that will survive best in this environment will be
_____________________ because _______________________________
___________________________________________________________ .
Population Data:
Allele Frequency
A
a
Generation 1
G2
G3
G4
G5
Population Data (After Surviving Numbers)
AA
Initial Pop. Size
G1 After
G2 After
G3 After
G4 After
G5 After
Aa
aa
Trial 2:
Environment 2: ____________________________
Hypothesis: The phenotype that will survive best in this environment will be
_____________________ because _______________________________
___________________________________________________________ .
Population Data:
Allele Frequency
A
a
Generation 1
G2
G3
G4
G5
Population Data (After Surviving Numbers)
AA
Initial Pop. Size
G1 After
G2 After
G3 After
G4 After
G5 After
Aa
aa
Analysis:
Graph your population numbers for each environment. Graphs can either
be completed on graph paper and attached to your lab or on the computer.
Write a paragraph (we have been working on this skill throughout the year)
describing the data and trends in the graphs.
Conclusions:
State whether the hypotheses were accepted or rejected based on the
data. Use specific numbers from the data to support this. Discuss how this
lab simulated what happens in nature with the evolution of organisms.
Summarize the process of natural selection (give examples) and discuss
the pros and cons of this lab. How could this lab be improved? Why is it
important to understand these concepts?
Vocab to consider:
- Natural selection
- Fitness
- Evolution
- Species
- Speciation
- Reproduction
- Mutation
- Allele
- Genotype
- Phenotype
- Speciation
- Gene pool
- Selection pressures
- Predator/Prey
- Camouflage
Works Cited: Put on separate page. Title centered on page.
Biggs, A., et. Al. Biology: The Dynamics of Life. New York: Glencoe
Science, 2004.
http://www.mhhe.com/biosci/genbio/virtual_labs/BL_12/BL_12.html. (2014).