Download Gene Frequency and Evolution

Living Environment
Student Work
BSC Lesson #18
Lesson 18. Gene Frequency &
Evolution
Name:
Period ______
Laboratory Experience ##
Worth ### Lab Minutes
Date :
Bridge
Evolution will dictate a change in gene frequencies. When a variation,
caused by either recombination or mutation, occurs in an organism, it may
provide a survival advantage. That advantage usually results in a
structural or behavioral change that will help an organism compete for
resources better.
Predict some structural and behavioral changes we might see in
organisms as they try to out compete those in their niche.
Objective:
Understand and
represent the
change in gene
frequency in
response to
environmental
changes through
models
Essential
Question:
How can the
environment
affect gene
expression and
cause a change
in gene
frequency?
Mini Lesson
Changes in gene frequency (how often a gene shows up in a population) is
often the result of environmental pressures. If there is a change in the
environment, often organisms will start to die off or find ways to deal with
that change. Some changes are small: an increase in the pH of a lake or
soil by 0.01 or an increase in temperature by 1ºF. Other changes are
drastic, like the impact of an asteroid that caused the extinction of the
dinosaurs or the eruption of a volcano that has lain dormant for thousands of years. No matter
the change, nature will respond.
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Living Environment
Student Work
BSC Lesson #18
Work Period
Below are different activities that deal with these environmental pressures. As you go through
them, focus on how there was a shift in genes over a period of time. Represent each of these as
a graph.
Stickleback Evolution: http://learn.genetics.utah.edu/content/variation/stickleback/
Rock Pocket Mice: http://learn.genetics.utah.edu/content/variation/comparative/
Paramecium Virtual Lab: http://glencoe.mcgrawhill.com/sites/dl/free/0078759864/383928/BL_04.html
Peppered Moth Simulation: http://www.techapps.net/interactives/pepperMoths.swf
What happened to the gene frequencies of the favored genes in each of the activities?
Did the favored populations grow indefinitely? Why or why not?
Summary
How can the environment affect gene expression and cause a change in gene frequency?
Closing
Sometimes gene expression is affected directly by the environment an organism lives in. We
saw a glimpse of this with the activity and skin color: people that live near the equator have an
advantage if they have darker skin color and the further you get from the equator the shift is to
lighter skin color.
Snowshoe hares are an example of this kind of gene expression. In the summer months,
snowshoe hares are brown and in the winter months they turn white. During spring and fall, they
are a combination of both colors. But these bunnies actually started out being either brown or
white.
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Living Environment
Student Work
BSC Lesson #18
1. Explain the adaptive value of these rabbits being able to change color based on their
environment.
2. Explain how the gene frequency of all three populations of rabbits changed over time
(both in words and as a graph)
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Living Environment
Student Work
Name:
BSC Lesson #18
Period ______ Date :
Independent Practice
Regents questions:
There is one on experiment with bunny and ice pack
One on change in pH of a bacteria population
The one on the lotus plants (short answer)
One on the bat population OR the rabbit population short answer where one is better
adapted than the other.
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Living Environment
Student Work
Name:
BSC Lesson #18
Period ______
Date :
Title of Lab: ______________________________________________________
Exploration
Use this space to record observations that relate to the question being investigated. Also record
researched facts that might relate to the investigation as well.
Question
Record your question that you will be investigating here. It is best to write it in a “Does
__________________ affect ________________? Format so the variables are easy to identify (first
line is always the independent variable, second line is always the dependent variable)
Identify your Variables
Independent Variable:
Dependent Variable:
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Living Environment
Student Work
BSC Lesson #18
Prediction/Hypothesis
Based on the question that you asked, record your thoughts on what the result will be and why. Use
the “I think ___________________________________, because ______________.” format.
Experimental Design
List the materials that you are going to use and the procedure (steps) you are going to take to test your
hypothesis.
Materials:
Procedure:
Data Collection
Use this space to organize and collect your data. Remember, data can be qualitative (descriptions,
words, observations) as well as quantitative (numbers, values). Use both kinds of data when you can.
Organize your data into a table with a title, make a graph whenever you can, and use the variables to
help you do this!
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Living Environment
Student Work
BSC Lesson #18
Data Analysis
Put your data into words. This will be a relationship of your variables: what happened to the dependent
variable when you changed the independent variable?
Evaluation
This is where you talk about your experiment. Discuss how your results compare to your hypothesis:
do you agree or disagree with your original thoughts and use evidence from your experiment to back
this up. Second, discuss sources of error (at least 2), or things that could have gone wrong in your
experiment. Finally, develop a further investigation question: based on what you found out in this
experiment, what else do you wonder about? Again, use your “Does ________ affect __________”
format for this question.
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