SJB Revised 4/17/2020 Page 1 of 6
Name: _____________________________________ Per. _____ Date: ___________________
Partner: ______________________________________________________________________
Learning Target: Natural Selection Activity
I Can…
Complete a simulation activity in order to explain how natural selection can affect the allele frequency of a single trait in a population through successive generations.
I Will…
 Complete the Natural Selection with “Teddy Grahams” activity o Use observation and data collection techniques

Discuss the results with a partner

Create a graphical representation of the data results

Use the experience, along with prior class learning, to analyze related questions and draw conclusions about the process of natural selection in evolution.
Background Information:
Predator-prey relationships can exert a significant selective pressure on the members of a population. For the prey, any trait that provides an advantage in surviving long enough to reproduce will be expected to be represented, over time, by a high percentage within the population.
In this simulation, you are a “Teddy Grahams” bear-eating predator.
There are two phenotypes of bears in the population: Y-ppah bears and Das bears who have different physical traits in the way that they hold their hands.

Y-ppah bears hold their hands high in the air. o U sually taste sweet
 A linked gene allele produces a sweet enzyme. o Easy to catch

Cannot run fast with hands in their air

Cannot see predators with hands blocking view.
Y-ppah Bear

Das bears hold their hands down low. o Usually taste bitter.

A linked gene allele produces a bitter enzyme. o Hard to catch

Can run fast with arms down.

Good peripheral vision to see predators.
Das Bear
Adapted from Natural Selection with “Teddy Grahams” by Lynn Marie Wartski http://www.accessexcellence.org/AE/AEC/AEF/1995/wartski_natural.php

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As a predator, you have learned eat mainly Y-ppah bears because they taste sweet and are easy to catch. You will only eat Das Bears if there aren’t any Y-ppah bears available, and only if you can catch them.
New bears are born every 'year' (during hibernation) from the surviving bears in the population provided there are at least two bears left in the population (does not matter which phenotype).
Materials:

Natural Selection Activity Packet with Data Collection and Analysis Questions
 “Teddy Grahams”

Cup

Napkins/Paper towels

Pencil

Calculator
Procedure:
1.
Read the Background Information for the activity.
2.
Working with a partner, obtain an initial population of “Teddy Grahams” bears. a.
Cup of a random population of “Teddy Grahams”.
3.
Separate the population into Y-ppah bears and Das bears . a.
Record the number of Y-ppah bears present in the initial population in Data Table 1. b.
Record the number of Das bears present in the initial population in Data Table 1. c.
Record the total number of bears present in the initial population ( Y-ppah + Das ) in Data
Table 1. i.
Note: For bear to count, you must be able to tell if it is an Y-ppah or Das bear and must be at least 50% or more intact.
4.
Eat four Y-ppah bears ; a.
If you have less than four Y-ppah bears , then eat the number of Y-ppah bears that you have.
5.
As long as you have two or more bears (any phenotype) left in your population, the bears will reproduce a new generation of bears. a.
If you have less than two bears left, your population is unable to reproduce and your simulation is over.
6.
Bring your cup up to the teacher to receive your next generation of “Teddy Grahams” bears.
7.
Combine the new bears to your existing population .
Adapted from Natural Selection with “Teddy Grahams” by Lynn Marie Wartski http://www.accessexcellence.org/AE/AEC/AEF/1995/wartski_natural.php

SJB Revised 4/17/2020 Page 3 of 6
8.
Repeat steps 3 – 7 for a total of six generations (initial P
1
population plus five new F generations).
9.
Calculate the percentage of each phenotype ( Y-ppah bears and Das bears ) per generation and complete Data Table 2. a.
Y-ppah bears percentage = # Y-ppah bears / Total # bears for each generation x 100 b.
Das bears percentage = # Das bears / Total # bears for each generation x 100
10.
Complete Graph 1 . Graphing the change in the percentage of Y-ppah bears from initial population over five generations.
11.
Complete Graph 2 . Graphing the change in the percentage of Das bears from initial population over five generations.
12.
Complete the Analysis Questions .
Round to nearest whole #
Data Table 1.
“Teddy Grahams” Bear Population Phenotype Variation
Generation # Y-ppah bears # Das bears Total # bears
P
1
Initial
F
1
F
2
F
3
F
4
F
5
Data Table 2.
“Teddy Grahams” Bear Population Phenotype Variation
Generation # Y-ppah bears # Das bears Total # bears
P
1
Initial
F
1
F
2
F
3
F
4
F
5
Adapted from Natural Selection with “Teddy Grahams” by Lynn Marie Wartski http://www.accessexcellence.org/AE/AEC/AEF/1995/wartski_natural.php

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Graph 1. P ercentage of Y-ppah bears from initial population over five generations
Graph 2. P ercentage of Das bears from initial population over five generations
Adapted from Natural Selection with “Teddy Grahams” by Lynn Marie Wartski http://www.accessexcellence.org/AE/AEC/AEF/1995/wartski_natural.php
[22 boxes high by
30 boxes wide]

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“Teddy Grahams” Natural Selection Analysis Questions
Refer to your notes on Principles of Natural Selection in addition to the data collected in this activity to answer the following questions.
1.
What was the variation (heritable difference) within the “Teddy Grahams” bear population?
2.
What was the adaptation of the variation that gave individuals an advantage in survival over others in the population?
3.
Explain why this adaptation was an advantage.
4.
What was the selective pressure that created the advantage of one version of the trait compared to the other version of the trait?
5.
Refer to Graph 1. Describe what happened to the Y-ppah bears in the population after five generations AND provide a logical explanation for this pattern.
6.
Refer to Graph 2. Describe what happened to the Das bears in the population after five generations AND provide a logical explanation for this pattern.
Adapted from Natural Selection with “Teddy Grahams” by Lynn Marie Wartski http://www.accessexcellence.org/AE/AEC/AEF/1995/wartski_natural.php

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7.
Think about the third key principle of natural selection; Overproduction . a.
Predict what might happen to the Das bears population over many generations if the same environmental conditions are maintained and same selective pressure remains in place. [Hint: Think back to our Population Unit with patterns of growth and carrying capacity.] b.
Predict what might happen to the population of “Teddy Grahams” bears if the number of
Y-ppah bears became so low that the “Teddy Grahams” bear-eating predator left to find food elsewhere.
EXTRA CREDIT: Which trait, Y-ppah or Das is the dominant version of the trait?
Explain your reasoning.
Adapted from Natural Selection with “Teddy Grahams” by Lynn Marie Wartski http://www.accessexcellence.org/AE/AEC/AEF/1995/wartski_natural.php