Change Happens:
Let’s Deal With It!
A Teachable Unit for Natural Selection
Deena Wassenberg and Rob Brooker, University of Minnesota
Lianna Etchberger and Greg Podgorski, Utah State University
Janet Batzli and Evelyn Howell, University of Wisconsin, Madison
Kimberly Hammond, University of California, Riverside
Mark Lyford, University of Wyoming, Laramie--Facilitator
1
Evolution
Large
topics in
Evolution
Origin of Life – Chemical
Evolution
Population Genetics
(Microevolution)
Darwin’s Theory
Speciation
(Macroevolution)
Large
learning
goals
Learning Goal
Students will understand that evolution is a heritable change in one or more
characteristics of a population or species across many generations
Sublearning
goals
Learning Goal
Students will understand the relationship between
natural selection and reproductive success
Learning
Outcomes
Activities
Assessments
Learning Outcome 1
Students will demonstrate
that they have overcome
common misconceptions
about natural selection using
diagrams and writing
Brainstorming
evolution
definition
Pre-test
and posttest
Dinosaur cartoon
minute paper
Clicker question:
What type of
selection?
Learning Outcome 2
Students will be able to
define and use
vocabulary related to
natural selection
Learning Outcome
3
Students will be
able to identify
different patterns of
natural selection
Classroom
evolution based on
fitness
Laboratory
Activities
Concept
map
Laboratory
report
Learning Outcome 4
Students will be able to
predict change in
population gene
frequencies in response to
natural selection
Students will take
vocabulary terms and make
a concept map
Homework
questions
Systematics
Learning Outcome 5
Students will be able to design an
experiment to demonstrate the
importance of reproductive
success associated with natural
selection
Mouse hemoglobin
scenario
Experimental
design paper
Design an experiment to test if
high altitude hemoglobin
confers fitness at high altitude
Draw a better dinosaur
cartoon: correcting
misconceptions
2
Evolution
Large
topics in
Evolution
Population Genetics
(Microevolution)
Large
learning
goals
Learning Goal
Students will understand that evolution is a heritable change in one or more
characteristics of a population or species across many generations
Sublearning
goals
Learning Goal
Students will understand the relationship between
natural selection and reproductive success
Learning
Outcomes
Activities
Assessments
Learning Outcome 1
Students will demonstrate
that they have overcome
common misconceptions
about natural selection using
diagrams and writing
Brainstorming
evolution
definition
Pre-test
and posttest
Dinosaur cartoon
minute paper
Draw a better dinosaur
cartoon: correcting
misconceptions
3
Evolution
Large
topics in
Evolution
Population Genetics
(Microevolution)
Large
learning
goals
Learning Goal
Students will understand that evolution is a heritable change in one or more
characteristics of a population or species across many generations
Sublearning
goals
Learning Goal
Students will understand the relationship between
natural selection and reproductive success
Learning
Outcomes
Learning Outcome 2
Students will be able to
define and use
vocabulary related to
natural selection
Students will take
vocabulary terms and make
a concept map
Activities
Assessments
Concept
map
4
Evolution
Large
topics in
Evolution
Population Genetics
(Microevolution)
Large
learning
goals
Learning Goal
Students will understand that evolution is a heritable change in one or more
characteristics of a population or species across many generations
Sublearning
goals
Learning Goal
Students will understand the relationship between
natural selection and reproductive success
Learning Outcome
3
Students will be
able to identify
different patterns of
natural selection
Learning
Outcomes
Classroom
evolution based on
fitness
Activities
Assessments
Clicker question:
What type of
selection?
5
Evolution
Large
topics in
Evolution
Population Genetics
(Microevolution)
Large
learning
goals
Learning Goal
Students will understand that evolution is a heritable change in one or more
characteristics of a population or species across many generations
Sublearning
goals
Learning Goal
Students will understand the relationship between
natural selection and reproductive success
Learning Outcome 4
Students will be able to
predict change in
population gene
frequencies in response to
natural selection
Learning
Outcomes
Activities
Laboratory
Activities
Assessments
Laboratory
report
Mouse hemoglobin
scenario
Homework
questions
6
Evolution
Large
topics in
Evolution
Population Genetics
(Microevolution)
Large
learning
goals
Learning Goal
Students will understand that evolution is a heritable change in one or more
characteristics of a population or species across many generations
Sublearning
goals
Learning Goal
Students will understand the relationship between
natural selection and reproductive success
Learning
Outcomes
Learning Outcome 5
Students will be able to design an
experiment to demonstrate the
importance of reproductive
success associated with natural
selection
Design an experiment to test if
high altitude hemoglobin
confers fitness at high altitude
Activities
Assessments
Experimental
design paper
7
Unit Sequence
Learning Goal
Students will understand the relationship
between reproductive
success and natural
selection
Outcomes 1 & 2
Outcomes 3 & 4
Outcome 5
Objectives and Overview
Pretest
CINS
Introduction to
Natural Selection
Form.
Assessment 1
Patterns of Selection
Form.
Assessment 1
Learning outcomes
1: Students will demonstrate that she/he has
overcome common misconceptions about natural
selection using diagrams and writing.
2. Students will be able to define terms and identify
factors that play a role in natural selection.
3. Students will be able to identify patterns of
natural selection.
4. Students should be able to quantitatively predict
changes in allele or genotype frequencies in a
population based on natural selection..
5. Students should be able to design an experiment
to demonstrate the importance of reproductive
success associated the natural selection.
Measures of Fitness
Form. Asses. 3
Form.
Asses. 4-6
…..
Post-Test
CINS
Formative assessments
1: Pretest - concept inventory for natural selection
2: One-minute paper - misconceptions in evolution
3: Change happens - class activity demonstrating
natural selection
4. Clicker question - what form of selection was
demonstrated?
5. Clicker questions - natural selection in deer mice
6. Posttest - concept inventory for natural selection
8
Concept inventory of natural
selection (CINS) Pre-test/Post-test
Sample question (1/20)
How did the different beak types first arise in the Galapagos finches?
a)
The changes in the finches’ beak size and shape occurred because
of their need to be able to eat different kinds of food to survive.
b)
Changes in the finches’ beaks occurred by chance, and when there
was a good match between beak structure and available food, those
birds had more offspring.
c)
The changes in the finches’ beaks occurred because the environment
induced the desired genetic changes.
d)
The finches’ beaks changed a little bit in size and shape with each
successive generation, some getting larger and some getting smaller.
Anderson, D.L., Fisher, K.M., & Norman, G.J. (2002). Development and Evaluation
of the Conceptual Inventory of Natural Selection. Journal of Research in
Science Teaching, 39, 952-978.
http://www.biologylessons.sdsu.edu/CINS6_03.pdf
9
What is biological evolution?
Brainstorm

A heritable change in one or more
characteristics of a population or species
across many generations
Viewed on a small scale relating to changes in a
single gene in a population over time (our focus)
Viewed on a larger scale relating to formation of new
species or groups of species
FA:
1
2
3
4 5 6
10
Evolution

Teachable unit flow chart:
The flow chart helps us to place our current
topic within the larger picture of evolution. Our
topic for the next couple of classes will be the
relationship between natural selection and
reproductive success.
11
Learning goal
Student will be able to understand that
evolution is a heritable change in one or
more characteristics of a population or
species across many generations

FA:
1
2
3
4 5 6
12
Learning exercise

To appreciate the general ideas about natural
selection that we might already have coming into
this course, let’s begin with a short learning
exercise.
13
AAAS 1999
Minute Paper:
1.
Examine cartoon.
2.
Explain the changes that occurred in the tree AND animal
using your current understanding of evolution by natural
selection.
3.
Individually, write your answer on small card and hand in.
4.
With a partner, list the assumptions being implied in the
cartoon.
14
Learning outcome 1: Student will overcome
common misconceptions about natural
selection using diagrams and writing.
Learning outcome 2: Student will be able to
define terms and identify factors that play a
role in natural selection.
15
Gene pool
All of the genes in a population
 Study genetic variation within the gene
pool and how variation changes from one
generation to the next
 Emphasis is often on variation in alleles
between members of a population

FA:
1
2
3
4 5 6
16
Population

Group of individuals of the same species
that an interbreed with one another
17
Natural selection in a population
We’re going to go through an active learning
exercise to appreciate some of the
general connections between genetic
variation, reproductive success, and
natural selection.
FA:
1
2
3
4 5 6
19
LOST
http://www.youtube.com/watch?v=nsmO2rLxIv0&mode=related&search=
20
Stand-up, sit-down natural
selection
1. Each new generation we all stand up.
 2. Individuals with green eyes, size 8 feet,
and short index fingers have children with
the same traits.
 3. The population size remains the same
each generation.

21
Learning outcome 3: Student should be able to
identify different patterns of natural selection.
22
What have we learned?
Has this population evolved?
23
Modern description of natural selection
1) Genetic variation arises from random mutations that may
alter the function of the protein.
2) Some alleles may encode proteins that enhance an
individual’s survival and reproductive success compared
to that of other members of the population
3) Individuals with beneficial alleles are more likely to
survive and contribute their alleles to the gene pool of
the next generation
4) Over the course of many generations, allele frequencies
of many different genes may change through natural
selection, thereby significantly altering the characteristics
of a population

Net result of natural selection is a population that is better
adapted to its environment and more successful at reproduction.
24


Some genotypes have greater reproductive
success, meaning that they contribute more
offspring that are viable to the next generation
compared with other genotypes.
Reproductive success depends on:
 1.
Ability to survive to reproductive age
 2. Ability to find a mate
 3. Fertility
25
Natural selection patterns
Directional selection
 Stabilizing selection
 Disruptive selection
 Balancing selection

FA:
1
2
3
4 5 6
26
Directional selection
Favors individuals at one extreme of a
phenotypic distribution that have greater
reproductive success in a particular
environment
 Initiators

 New
favored allele introduced
 Prolonged environmental change
27
Figure 24.3
28
Stabilizing selection
Favors the survival of individuals with
intermediate phenotypes
 Extreme values of a trait are selected
against
 Clutch size

 Too
many eggs and offspring die due to lack
of care and food
 Too few eggs does not contribute enough to
next generation
29
Figure 24.4
30
Disruptive selection
Favors the survival of two or more different
genotypes that produce different
phenotypes
 Likely to occur in populations that occupy
diverse environments
 Members of the populations can freely
interbreed

31
Figure 24.5
32
Balancing selection
Maintains genetic diversity
 Balanced polymorphism

 Two
or more alleles are kept in balance, and
therefore are maintained in a population over
the course of many generations

2 common ways
 For

a single gene, heterozygote favored
Heterozygote advantage – HS allele
 Negative

frequency-dependent selection
Rare individuals have a higher fitness
33
Figure 24.6
34
Clicker question: Our class exercise
involved eye color, foot size, and finger
length. With regard to changes in
index finger length in our population, is
this an example of:
A.
B.
C.
D.
Directional selection
Stabilizing selection
Disruptive selection
Balancing selection
FA:
1
2
3
4 5 6
35
Sexual selection
Form of natural selection
 Directed at certain traits of sexually
reproducing species that make it more
likely for individuals to find or choose a
mate and/or engage in successful mating
 In many species, affects male
characteristics more intensely than it does
female

36
Figure 24.7
37






Explains traits that decrease survival but increase
reproductive success
Male guppy (Poecilia reticulata) is brightly colored
compared to the female
Females prefer brightly colored males
In places with few predators, the males tend to be
brightly colored
In places where predators are abundant, brightly colored
males are less plentiful because they are subject to
predation
Relative abundance of brightly and dully colored males
depends on the balance between sexual selection, which
favors bright coloring, and escape from predation, which
favors dull coloring
38
Learning outcome 4: Student should be able
to quantitatively predict changes in allele or
genotype frequencies in a population based
on natural selection.
Learning outcome 5: Student should be able
to design an experiment to demonstrate the
importance of reproductive success
associated the natural selection.
39
Quantitative predictions of natural
selection

We now turn to natural selection on a
quantitative level, which requires that we
consider allele frequencies and Darwinian
fitness.
FA:
1
2
3
4 5 6
40
Allele and genotype frequencies

Related but distinct calculations
41
Darwinian fitness
Relative likelihood that a genotype will
contribute to the gene pool of the next
generation as compared with other
genotypes
 Measure of reproductive success
 Hypothetical gene with alleles A and a

 AA, Aa,
aa
42

Suppose average reproductive successes
are…
 AA 
5 offspring
 Aa  4 offspring
 Aa  1 offspring

Fitness is W and maximum is 1.0 for
genotype with highest reproductive ability
 Fitness
of AA: WAA = 5/5 = 1.0
 Fitness of Aa: WAa = 4/5 = 0.8
 Fitness of aa: Waa = 1/5 = 0.2
43
Mice and hemoglobin
Certain populations of deer mice are
found to be polymorphic with regard to a
gene that encodes a subunit of the
oxygen-carrying protein, hemoglobin
 Hh- high altitude allele (high oxygen
affinity)
 Hl- low altitude allele (low oxygen affinity)

44
Deer Mouse (Peromyscus maniculatus)
• Cosmopolitan in North America
• Live & breed in harsh conditions across all altitudes
(0 - 4000 m)
• Gives birth to large litters (4-8 pups)
• Genetic polymorphisms in a-globin subunits
M.A. Chappell
45
1
0.8
0.6
Hl allele frequency
(“Low altitude” allele)
0.4
0.2
0
0
1000
2000
3000
4000
Altitude (m)
(each of the 52 symbols is
a different population of mice)
Data from Snyder (1981)
46
On the next series of slides, you
will be asked to use the information
from these data to predict changes
due to natural selection.
FA:
1
2
3
4 5 6
47
Q1. What is the approximate allele frequency for the Hl
allele in the mouse population at the red arrow?
1
0.8
0.6
Hl
allele frequency
(Low altitude)
0.4
0.2
0
0
1000
2000
3000
4000
Altitude (m)
(each of the 52 symbols is
a different population of mice)
Data from Snyder (1981)
48
Q2. Based on the allele frequency you estimated from question 1, draw a
graph that would describe what would happen if the mouse population
at the arrow was transported to 4000 m and there were geographic
barriers that prevented the population from moving to a lower altitude.
1
0.8
0.6
Hl
allele frequency
0.4
0.2
0
Generations
49
Q3. Make a curve similar to the one in question 2, but plot the frequency
of the Hh allele instead.
Q4. Take home assignment. The curves you have drawn in questions 2
and 3 were under the hypothesis that mice carrying the Hh allele have
a higher reproductive success at high altitude. Write a paper guided
by the rubric available on our web site. Be sure to describe your
methods and indicate what type of data you would expect if the
hypothesis was correct. The rubric will be used in assessing your
work.
50
AAAS 1999
1.
2.
Individually, apply your knowledge of evolution by natural
selection.
List the assumptions being applied in the cartoon and
redraw/revise the drawing to reflect these assumptions.
FA:
1
2
3
4 5 6
51
Elements of a correct answer.
Time
52

Images from Biology I-e, McGraw Hill
2008
53