Evolution 3e SB v5

This content is copyrighted © by the Regents of the University of
California and is available through the Lab-Aids Portal. By using
this content, users acknowledge the following:

• Users may not electronically transfer or provide access to
this content, nor make this available on an LMS or similar
system, except for their own use within a school district or
their own classrooms, behind a password protected site.

• Users may not modify this content except as noted within the
product/content.

• Users may not use this content for any unlawful purpose and
are liable for any and all claims arising from any violation
of this agreement.

ISSUES AND Evolution
LIFE SCIENCE

THIRD EDITION

REVISED FOR THE NGSS



ISSUES AND Evolution
LIFE SCIENCE

THIRD EDITION

REVISED FOR THE NGSS

THE LAWRENCE HALL OF SCIENCE
UNIVERSITY OF CALIFORNIA, BERKELEY

This book is part of SEPUP’s Issues and Science course sequence. For more
information about this sequence, see the SEPUP and Lab-Aids websites.

ISSUES AND EARTH SCIENCE

ISSUES AND LIFE SCIENCE

ISSUES AND PHYSICAL SCIENCE

Additional SEPUP instructional materials include
SEPUP Modules: Grades 6–12
Science and Sustainability: Course for Grades 9–12
Science and Global Issues: Biology: Course for High School Biology

This material is based upon work supported by the National Science Foundation under Grants
9554163 and 0099265. Any opinions, findings, and conclusions or recommenda tions expressed
in this material are those of the authors and do not necessarily reflect the views of the National
Science Foundation.

For photo and illustration credits, see page 134, which constitutes an extension of this
copyright page.

The preferred citation format for this book is SEPUP. (2017). Issues and Life Science: Evolution.
Lawrence Hall of Science, University of California at Berkeley. Ronkonkoma, NY: Lab-Aids, Inc.

Third Edition

Q2 3 4 5 6 7 8 9 21 20 19 18 17

© 2017 The Regents of the University of California

ISBN: 978-1-63093-467-5
v5

SEPUP
Lawrence Hall of Science

University of California at Berkeley

Berkeley CA 94720-5200

email: [email protected]
website: www.sepuplhs.org

Published by

17 Colt Court
Ronkonkoma NY 11779
Website: www.lab-aids.com

A Letter to Issues and Life Science Students
As you examine the activities in this book, you may wonder, “Why does this book
look so different from other science books I’ve seen?”The reason is simple: it is a
different kind of science program, and only some of what you will learn can be
seen by leafing through this book!
Issues and Life Science uses several kinds of activities to teach science. As you
conduct these activities, you will engage in the same practices used by scientists to
understand the natural world and by engineers to solve problems. For example,
you will design and conduct an experiment to investigate how genes and the envi-
ronment affect the growth and development of plants.You will analyze and
interpret real data to explore the effects of an introduced species. And you will
model how species change over time and evolve into new species. A combination
of laboratories, investigations, readings, models, scientific debates, role plays, and
projects will help you develop your understanding of science and the relevance of
physical science to your interests.
You will find that important scientific ideas come up again and again in different
activities throughout the program.You will be expected to do more than just
memorize these concepts: you will be asked to develop explanations and apply
them to solve problems. In particular, you will improve your decision-making
skills by using evidence to weigh outcomes and to decide what you think should
be done about the scientific issues facing our society.
How do we know that this is a good way for you to learn? In general, research on
science education supports it. In particular, many of the activities in this book were
tested by hundreds of students and their teachers, and then modified on the basis
of their feedback. New activities are based on what we learned in classrooms using
the materials and on new research on science learning. In a sense, this entire book
is the result of an investigation: we had people test our ideas, we interpreted the
results, and we then revised our ideas! We believe the result will show you that
learning more about science is important, enjoyable, and relevant to your life.

SEPUP Staff

v

ISSUES & LIFE SCIENCE THIRD EDITION
Director: Barbara Nagle
Co-Director: John Howarth
Coordinator: Janet Bellantoni

AUTHORS
Wendy Jackson, Tiffani Quan, Barbara Nagle, Manisha Hariani

OTHER CONTRIBUTERS
Asher Davison, Daniel Seaver

PRODUCTION
Coordination, Design, Photo Research, Composition: Seventeenth Street Studios
Production Coordinator for Lab-Aids: Hethyr Tregerman
Editing: Kerry Ouellet

vi 

F I E L D T E S T C E N T E RS 
The classroom is SEPUP’s laboratory for development.We are extremely appreciative of
the following center directors and teachers who taught the program during the 2003–04
and 2004–05 school years. These teachers and their students contributed s­ ignificantly to
improving the first edition of the course. Since then, Issues and Life ­Science has been used
in thousands of classrooms across the United States.This third edition is based on what we
have learned from teachers and students in those classrooms and in the Revision Centers
listed on the next page. It also includes new data and information, so the issues included
in the course remain fresh and up-to-date.

REGIONAL CENTER, SOUTHERN CALIFORNIA
Donna Markey, Center Director
Kim Blumeyer, Helen Copeland, Pat McLoughlin, Donna Markey,
Philip Poniktera, Samantha Swann, Miles Vandegrift

R E GI O N A L C E N T E R, IOWA
Dr. Robert Yager and Jeanne Bancroft, Center Directors
Rebecca Andresen, Lore Baur, Dan Dvorak, Dan Hill, Mark Kluber, Amy Lauer,
Lisa Martin, Stephanie Phillips

REGIONAL CENTER, WESTERN NEW YORK
Dr. Robert Horvat, Center Director
Kathaleen Burke, Dick Duquin, Eleanor Falsone, Lillian Gondree, Jason Mayle,
James Morgan, Valerie Tundo

J E F F E R S O N C O U N T Y, KENTUCKY
Pamela Boykin, Center Director
Charlotte Brown, Tara Endris, Sharon Kremer, Karen Niemann,
Susan Stinebruner, Joan Thieman

LIVERMORE, CALIFORNIA
Scott Vernoy, Center Director
Rick Boster, Ann Ewing, Kathy Gabel, Sharon Schmidt, Denia Segrest,
Bruce Wolfe

QUEENS, NEW YORK
Pam Wasserman, Center Director
Gina Clemente, Cheryl Dodes, Karen Horowitz, Tricia Hutter, Jean Rogers,
Mark Schmucker, Christine Wilk

TUCSON, ARIZONA
Jonathan Becker, Center Director
Peggy Herron, Debbie Hobbs, Carol Newhouse, Nancy Webster

INDEPENDENT
Berkeley, California: Robyn McArdle
Fresno, California: Al Brofman
Orinda, California: Sue Boudreau, Janine Orr, Karen Snelson
Tucson, Arizona: Patricia Cadigan, Kevin Finegan

  vii

REVISION CENTERS
Chicago, Illinois: Bejaza Duskic, Francis Panion, Robert Troher
Elmhurst, Illinois: Kelly Biala

viii 

Contents

Evolution

1 i n v e s t i g at i o n  11 i n v e s t i g at i o n 
The Full Course 3 Family Histories 57

2 modeling 12 i n v e s t i g at i o n 
Hiding in the Background 7 A Whale of a Tale 63

3 r o l e p l ay  13 i n v e s t i g at i o n 
A Meeting of Minds 11 Embryology 67

4 m o d e l i n g  19 14 ta l k i n g i t o v e r  71
Battling Beaks The Sixth Extinction?

5 m o d e l i n g  15 reading 
Mutations: Good or Bad? 25 Bacteria and Bugs:
Evolution of Resistance 77
6 co m p u t e r s i m u l at i o n  31 81
Mutations and Evolution 35 16 i n v e s t i g at i o n  85
Manipulating Genes
7 v i e w a n d r e f l e c t  
Origins of Species 17 projec t 
Evolution and Us
8 re adi ng 
History and Diversity of Life 39

9 l a b o r ato ry  Unit Summary 87
Fossil Evidence
47 Appendices 91

10 i n v e s t i g at i o n  53 Glossary 125
Fossilized Footprints Index 129

Credits 134

  ix



Evolution

It was kenya’s fourth visit to the pet store. Ever since she decided she
wanted a pet lizard for her birthday, she had tried to come every day. She
still hadn’t decided which lizard she would like to have—and her birthday
was less than a week away!

“Excuse me, young lady. Can I help you?” asked the sales clerk behind the
counter.

“I want a lizard for my birthday,” replied Kenya. “But I can’t decide which
one I like best. There are so many different kinds—and they look so
different.”

“Some of them eat different foods, too,” added the sales clerk.

“I don’t understand how there can be so many different kinds of the same
animal,” said Kenya. “It’s amazing! I wonder how it happened.”

•••

Have you ever wondered about the variety of organisms on Earth? How did
they evolve? How are they related? Scientists investigate these questions by
looking at patterns in data, gathering evidence for cause-and-effect rela-
tionships, using models, and constructing explanations for such phenomena
as the evolution of new species and the extinction of other species. In this
unit, you will explore one such explanation that is so universal, it has become
a scientifically accepted theory: Charles Darwin’s theory of evolution by
natural selection. You will learn how populations of organisms change over
time and how new species arise while others go extinct. You will learn to
interpret the many sources of evidence for the evolution of life on Earth now
and in the past. You will also explore how evolution impacts us every day
and how we can affect the patterns of evolution.

1 The Full Course
i n v e s t i g at i o n

Sasha has a serious respiratory infection. Her doctor has done tests that
show the infection is caused by bacteria and has prescribed antibiotics to
help fight the infection.

“Sasha, I think you will start to feel better in a few days, but it’s important
you keep taking all the medicine even after you feel better. You must finish it
all. Don’t stop, and don’t miss doses,” warned Dr. Torres.

“Why?” she asked. “I don’t keep taking other medicines after I feel better.”

“There’s a real crisis developing with antibiotics. People take them when
they don’t need them, or take them for a while and then stop. This causes
bacteria to evolve antibiotic resistance. Doctors and researchers are very
worried about this.”

“What happens when the bacteria are resistant?” asked Sasha’s mother.

Dr. Torres replied, “The antibiotics don’t work against the resistant bacteria.
Last year our clinic had four patients with infections we used to be able to
fight easily! Three of those patients had to stay in the hospital and take anti-
biotics for a very long time before they got better. The other patient didn’t
make it.”

“You know, I just saw a story about that on TV,” said Sasha’s mother.

“I’m beginning to understand that antibiotics are different than other
medicines. I’ll be sure to take all the pills!” said Sasha.12

Streptococcus bacteria in its natural
environment, the human throat

12 NNGGLLSS44BC11 EVOLUTION 3

ACTIVITY 1  THE FULL COURSE

Antibiotics are chemical substances that help your body fight off
an infection by killing harmful bacteria. A small number of bacteria
in any population may not be affected by the antibiotic as quickly as
the rest of the population. These bacteria, which are more resistant
to the treatment, continue to grow and reproduce if doses of antibiotic
are missed. In this activity, you will use a model to explore how bacteria
have changed over time to become resistant to many antibiotics.

GUIDING QUESTION

What happens when a person does not take antibiotics as
prescribed?

MATERIALS

For each pair of students
1 set of 50 disks (20 green, 15 blue, 15 orange)
4 colored pencils (including green, blue, orange)
1 number cube

For each student
1 Student Sheet 1.1, “Bacteria Graphs”

A Bacterial Infection

Imagine that you are sick with a bacterial infection. Your doctor prescribes
an antibiotic to be taken every day for eight days.

Colored disks represent the harmful bacteria that are in your body:

Disease-Causing Bacteria Represented by
Least resistant bacteria green disks
Resistant bacteria blue disks
Extremely resistant bacteria orange disks

Each time you toss the number cube, it is time to take the antibiotic. The
number on the number cube tells you what to do.

4 EVOLUTION

THE FULL COURSE  ACTIVITY 1

PROCEDURE

1. You and your partner should begin with 20 disks: 13 green,
6 blue, and 1 orange.These disks represent the harmful bacteria
living in your body before you begin to take the antibiotic. Set
the extra disks aside for now.34

2. Make a data table in your science notebook similar to the one

below. 5

Number of Harmful Bacteria in Your Body

Extremely
Least resistant Resistant resistant bacteria
Toss number bacteria (green) bacteria (blue) (orange) Total

Initial 13 6 1 20

1

2

3

4

5

6

7

8

3. It is time to take your antibiotic. Toss a number cube and follow
the instructions in the Number Cube Key below.

Number Cube Key

YOUR TOSS WHAT HAPPENED WHAT TO DO
1, 3, 5, 6
You took the antibiotic on time, so bacteria are Remove 5 disks: remove all of the green disks
2, 4 being killed! first, then the blue, then the orange.

You forgot to take the antibiotic. Do nothing.

4. The bacteria are reproducing all of the time! If one or more
bacteria of a particular type are still alive in your body, add
1 disk of that color to your population.

For example, if you have resistant (blue) and extremely resistant
(orange) bacteria in your body, add 1 blue disk and 1 orange
disk to your bacterial population.

5. Record the number of each type of bacteria in your body in the
table in your science notebook.

453 ENSELGLRSTSPS6D8NM31 1

EVOLUTION  5

ACTIVITY 1  THE FULL COURSE

6. Repeat Steps 3–5 until you have completed your table.
7. Use the data in your table to graph the population for each type

of bacteria and the total number of bacteria on Student Sheet 1.1,
“Bacteria Graph.” Use different colored pencils to represent each
type of bacteria.6

ANALYSIS

1. Describe what happened when you or a classmate
a. remembered to take the antibiotic according to the instructions.
b. missed several doses of the antibiotic.78910

2. Provide an explanation for these results.11
Hint: How do bacteria differ, and what is happening to

the bacteria when they are exposed to antibiotics in their
environment?
3. Reflection: Have you or any of your family members ever taken
an antibiotic? If so, did you follow instructions? How has this
activity affected the way you will take antibiotics in the future?

861791 0 1 SNNMNMEGGGAAACCSSRSPPPCCOA66PCDBDAAE511112

6 EVOLUTION

2 Hiding in the Background
modeling

In the last activity, you explored how the presence of antibiotics
in the environment affects the survival of bacteria depending on
their resistance to antibiotics. In this activity, you will use a model
to explore how an environment that includes predators affects the
survival of individuals of an imaginary species, toothpick worms.
You will focus on differences in just one feature, the color of the
worms. The versions of a feature, such as color, are called traits.
Differences in traits are called variations. The two possible color
traits in worms are green and beige. 121314

GUIDING QUESTION

How does the environment affect an individual’s probability
of survival and successful reproduction?

111342 NNNGGGLLLSSS442ABC121

Camouflaged animals

EVOLUTION  7

ACTIVITY 2  HIDING IN THE BACKGROUND

MATERIALS

For each group of four students
2 paper bags
50 green toothpicks
50 beige toothpicks

For each student
1 clear plastic bag
1 Student Sheet 2.1, ”Worm Populations”
1 piece of graph paper

The Toothpick Worm Model

Imagine that you are a bird that eats small worms. In this activity, toothpicks
will represent the worms that you eat. There are two traits for worm color:
beige and green. Different color toothpicks represent these two traits.

PROCEDURE

1. Label one of the paper bags “Worms” and the other “Reserve
Toothpicks.”1516

2. Each toothpick represents a worm. Count 25 green “worms” and
25 beige “worms,” and place them into the paper bag labeled
“Worms.” This is the initial number of worms in the initial popu-
lation, also called the first generation. These amounts are already
marked for you in both tables on Student Sheet 2.1, “Worm
Populations.”

3. Place the rest of the toothpicks into the bag labeled “Reserve
Toothpicks.”

4. Shake the “Worms” bag to mix the worms.
5. As directed by your teacher, scatter the worms on the “ground.”
6. You are going to play the role of a bird predator that preys upon

worms.Your group must “eat” (pick up) 40 worms, so decide how
many worms each member of your group will eat.You must pick
up the first worms that you see, regardless of the color, and place
them in the clear plastic bag, which represents the bird’s stomach.

1156 NELGRSSP6D8M3 1

8 EVOLUTION

HIDING IN THE BACKGROUND  ACTIVITY 2

7. Count the total numbers of green and beige worms that survived EVOLUTION  9
in the habitat. Record these totals in Row 2 of the table for
Generation 1 on Student Sheet 2.1.

8. Each surviving adult worm is reproducing, and each of them has
4 offspring that are identical to the parent. On Student Sheet
2.1, multiply the numbers of green and beige surviving adult
worms by 4. For example, if you had 7 green worms still alive,
there would be a total of 28 green offspring worms (7 x 4 = 28).
Record this number in Row 3.

9. Add Rows 3 and 4 to get the total number of surviving adults
and offspring for green worms and beige worms. Record this
number in Row 4. This number represents the number of green
worms and beige worms that are present in the habitat at the
start of the second generation. Copy these numbers into Row 1
of the table for Generation 2.

10. Count out the number of green and beige toothpicks shown in
Row 1 for Generation 2, and repeat Steps 6–8, but this time
completing the table for Generation 2.

11. Repeat the steps again for Generation 3, the final generation in
this simulation.

12. Create a graph showing the results from the start of Generation 1
through the end of Generation 3. 1718

ANALYSIS

1. Look at your results.1920212223

a. Compare the number of green worms to the number of
beige worms using a ratio. For example, the ratio of green
to beige worms in Generation 1 is 25:25, or 1:1.

b. Calculate the percentage of green worms and beige worms in
each generation.

c. Describe how the percentage of green and beige worms
changed over the three generations.

d. Did any individual worm change color? Explain.
e. Why do you think you observed this pattern?
Hint: A pattern is something that happens in a repeated and

predictable way. Provide a cause-and-effect explanation for
this pattern.

11221229782301 NMSSNMNEEGGGAAAASSCSRSSPPPPCAOAU66PDDBDAMA1511111

ACTIVITY 2  HIDING IN THE BACKGROUND

2. Imagine that you performed this simulation for another genera-
tion. What do you predict the percentage would be of green and
beige in the population of worms? Explain your prediction.24

3. Due to a drought, grass begins to dry out and die, leaving only
dead grass stalks. What is likely to happen to the percentage of
green and beige worms? Explain.252627

4. Compare and contrast your findings with those from the previous
activity, “The Full Course.” How are they similar? How are they
different?

22225647 NNNNGGGGLSCSPPSCDC2CAEME2221

10 EVOLUTION

3 A Meeting of Minds
r o l e p l ay

In the previous activities, you used models to explore how factors in
the environment can influence the survival of organisms. In the first
model, you explored how chemical substances in the environment
affect bacteria. In the second model, you explored how predation
affects toothpick worms. In your models, you explored what happens
over a few generations. What happens when these environmental
factors continue to affect a population of organisms for many more
generations? In this activity, you will compare two different explana-
tions for how species change over time.2829

GUIDING QUESTION

How does natural selection happen?

2298 NNGGLLSS44BC11

Charles Darwin (left) and Jean Baptiste Lamarck (right)

EVOLUTION  11

ACTIVITY 3  A MEETING OF MINDS

MATERIALS

For each student
1 Student Sheet 3.1, “A Meeting of Minds”

PROCEDURE

1. Assign a role for each person in your group. Assuming there are
four people in your group, each of you will read one role.
• Charles Darwin, 19th-century scientist
• Isabel Matos, science reporter for Station W-EVO
• Jean-Baptiste Lamarck, 19th-century scientist
• Wendy Chin, middle school student

2. Read the role play on the next pages aloud. As you read, think
about what each character is saying.

3. Mark whether you think scientists today would agree or disagree
with the statements on Student Sheet 3.1, “A Meeting of Minds.”30

4. Discuss the statements with your group.

HOW DO SPECIES CHANGE OVER TIME?

30 SELTIIsAa1 bel Matos: In today’s episode of “Time Travel
News,” we have brought together
two of the first scientists to
publish ideas on how species
evolve, or change over time.
Visiting us from the 19th century
are Jean-Baptiste Lamarck and
Charles Darwin. Monsieur
Lamarck, let’s start with you.

Jean-Baptiste Lamarck: I was one of the first to recognize
that species change over time. In
1809, I proposed the first theory
of how species change over time.
Allow me to explain my theory.
Let’s begin by talking about
giraffes.Wendy, why do you think
giraffes have such long necks?

12 EVOLUTION

A MEETING OF MINDS  ACTIVITY 3

Wendy Chin: To reach leaves at the tops of trees, I guess. They have to be able to
get food.

Lamarck: Quite right. I began to wonder how giraffes’ necks became so long.
My theory was that giraffes stretched their necks by reaching for
leaves that were higher and higher on the trees. This made their
necks longer. Then, when they had babies, their babies had longer
necks too. Look—this sketch helps explain my ideas.

Lamarckian Evolution

This is an adult giraffe. The giraffe reaches for The use of the neck causes The offspring of the giraffe
leaves slightly out of reach. it to lengthen slightly. also has a longer neck.

Wendy: Shouldn’t a theory be based on evidence?

Matos: Mr. Lamarck, did you ever see an adult giraffe grow its neck longer?

Lamarck: Of course not. My idea was that the growth was very small, too small
to measure in one generation.

Charles Darwin: I’d like to explain another theory, called natural selection. Alfred
Russel Wallace and I constructed this theory at about the same time.
We also noticed that not all animals of the same type have the same
features. Take horses, for instance.

Wendy: Oh, I know what you mean! There are horses of different sizes and
colors, but they are all one species and can interbreed.

EVOLUTION  13

ACTIVITY 3  A MEETING OF MINDS

Darwin: Exactly—and the same is true of giraffes. Have you noticed that
animals in the same species look different, or varied? This is important
because in the wild, some animals in each species usually die every
year. Only animals that survive can give birth to offspring. Now, what
feature of a giraffe might help it to survive and live to reproduce?

Lamarck: Its neck, of course! As I said before, it must stretch from being used
so vigorously. Giraffes can then pass on the longer necks to their
children.

What differences do you
observe in these giraffes of
the same species?

Matos: But Mr. Lamarck, modern scientists have found no evidence for your
hypothesis that parents can pass acquired traits to their offspring.
Consider professional wrestlers.They build muscles by lifting weights.
But their babies are no stronger than other babies. If these babies want
to have muscles like their parents, they have to pump a lot of iron, too!

Darwin: But just like human babies, not all giraffes are the same. They have
slight differences in all their characteristics, including neck length.

Lamarck: So you’re saying any giraffe that happens to have a slightly longer
neck can eat leaves that are higher in a tree than a shorter-necked
giraffe can and, therefore, is more likely to survive.

Wendy: So the longer-necked giraffes are more likely to live longer because
they can reach more food. If more of these giraffes live longer, they
can produce more offspring!

Darwin: That’s right. Animals with certain features, such as giraffes with
longer necks, are more likely to live to adulthood and have more
babies. We call that process natural selection. Here’s a sketch of how
it works:

14 EVOLUTION

A MEETING OF MINDS  ACTIVITY 3

Darwinian Evolution (Natural Selection)

Giraffes with longer necks tend to Longer-necked giraffes are more likely . . . and reproduce. The offspring
reach leaves more easily. to eat enough to survive . . . inherit their parents’ longer necks.

Wendy: But why will the offspring of longer-necked giraffes have longer
necks, too?

Matos: Well, tall parents are more likely to have tall children, aren’t they?
The same is probably true of giraffes.

Darwin: According to my theory, each new generation of giraffes has, on the
average, slightly longer necks than the generation before.31

Lamarck: But not because they stretched their necks? Only because the longer-
necked giraffes were more likely to survive and reproduce?

Wendy: I get it. Individual animals don’t change, but over very long periods
of time, the population of an entire species does.

Lamarck: But, Mr. Darwin, can your theory of natural selection explain why
extinction occurs?

Darwin: I believe so. Consider the mammoth, which became extinct a few
thousand years ago. Why didn’t mammoths keep changing and
continue to survive?

Wendy: There are several theories about that. They became extinct during a
time when the global climate was warmer than it had been before.
The changing climate may have affected the mammoth’s food
supply, and human hunters may have contributed to the extinction.

31 NGCCPA1

EVOLUTION  15

ACTIVITY 3  A MEETING OF MINDS

Matos: So a species becomes extinct when it doesn’t survive an environ-
mental change. No individuals in the population have the traits
necessary to survive.

Darwin: That’s all it is. The variation in the population isn’t enough to with-
stand environmental changes. In fact, sooner or later, most species
become extinct.

Wendy: Let me get this straight. As time passes, species change. The way
this occurs is by natural selection—some individuals in a population
happen to be better suited to the environment and they’re more
likely to survive and reproduce.

Lamarck: As a result, the population as a whole over many generations comes
to have the trait, such as a giraffe’s long neck, that increases survival.
A trait that becomes more common because it increases survival and
reproduction is called an adaptation.3233

Matos: Today, we know that we pass on characteristics like longer necks
to our offspring through genes. Genes don’t change because you
exercise your neck.

Darwin: Tell us more about these genes.

Wendy: I learned about genes in school. Genes are parts of our cells that we
inherit from our parents. They determine our traits, like hair color
and eye color.34

Lamarck: Fascinating. I would like to learn more about this.

Darwin: Without this modern evidence, I hesitated to publish my theory
for years, until Wallace sent me a brief paper containing the same
ideas. Within a few years of our publications, our ideas were widely
accepted.

Matos: So scientists now understand that natural selection is the process
that results in the survival and reproductive success of individuals
that have inherited traits that are adapted to their current environ-
ment. Thank you, Mr. Lamarck and Mr. Darwin. Viewers, I hope
you’ve enjoyed meeting people from our past. Join us next week for a
scintillating conversation with Marie Curie, the first woman scientist
to receive a Nobel Prize.35

33333524 NNNNGGGGLCLLSSSC344CBBCE2112

16 EVOLUTION

A MEETING OF MINDS  ACTIVITY 3

ANALYSIS

1. Compare and contrast Lamarck’s and Darwin’s theories of
change over time.36
a. What are the similarities? What are the differences?
b. Why do scientists find Darwin’s theory more convincing? 37

2. Explain why earthworms are beige or brown and not green3839
a. using Darwin’s theory of natural selection.
b. using Lamarck’s theory of change.

3. Explain whether Darwin’s theory or Lamarck’s theory is a better
explanation for your results in the previous activity, “Hiding in
the Background.”

Hint: Be sure to cite evidence from the activity.4041

344333160897 ENNNSEELLGGGWARSSSSSHPPPE6CEC68XA8EE219222

EVOLUTION  17



4 Battling Beaks
modeling

As you learned in the last activity, “A Meeting of Minds,”
Darwin’s theory of natural selection explains how species
change over time, or evolve. This process of change over time is
called evolution. But for natural selection to lead to evolution, there
must be differences among individuals within that species. In the
toothpick worms example, some were green while others were beige.
In the bacteria example, some individuals were highly resistant to
antibiotics, some were slightly resistant, and others were not resistant
at all. In this activity, you will explore the role that these differences
play in natural selection.42434445

GUIDING QUESTION

What role does genetic variation play in the process of
natural selection?

44444253 NNNNGGGGLLLLSSSS3424AABC1121 Why do these four different bird
species have such different beaks?

EVOLUTION  19

ACTIVITY 4  BATTLING BEAKS

MATERIALS

For each group of four students
4 plastic forks with 1 tine
4 plastic forks with 2 tines
4 plastic forks with 4 tines
4 plastic cups
1 number cube
1 Battling Beaks Arena
1 cup of “wild loops”

For each student
1 piece of graph paper

The Forkbird Model

In this activity, you will role play a single species called forkbirds. Forkbirds
feed by either spearing or scooping their food. During feeding time, each
bird gathers “wild loops” and immediately deposits them into its “stomach”
before gathering more food. Your goal is to gather enough food to survive
and reproduce. This will allow you to pass your genes on to another gener-
ation. Occasionally, a forkbird offspring will have a genetic mutation that
makes it look different from its parent.

PROCEDURE 46

1. Make a data table in your science notebook to keep track of the
three kinds of forkbirds: 1-tined, 2-tined, and 4-tined.Your table
should have enough rows for the initial generation and 10 subse-
quent generations.47

2. The initial forkbird population has beaks with only 2 tines. Each
person in your group should begin the activity with a 2-tined
fork. Record the initial population of each type of forkbird in
your data table.

3. Your teacher will tell you when feeding time begins, and then all
of the forkbirds can feed.

4. When feeding time ends, count the number of wild loops eaten by
each forkbird.

4467 ENLGRSSP6D8M3 1

20 EVOLUTION

BATTLING BEAKS  ACTIVITY 4

5. Within your group, the two forkbirds that gathered the most
food survive to reproduce. (If there is a tie for second place, then
three forkbirds survive. The two forkbirds that tie should keep
their forks and skip Step 6.)

6. Depending on whether you survived or not in Step 5, complete
step a or b as follows:

a. The group members whose forkbirds did not survive should
set their forks aside. They now assume the role of the
offspring in the next round.

b. The two surviving forkbirds (or one forkbird if there was a
tie for second place) should each toss the number cube to see
if any mutations occur when they reproduce. A mutation is
a change in the sequence of a gene. Use the table below to
determine the type of beak of the offspring of each surviving
forkbird. They should hand a new fork with the correct
number of tines to the group members who are now playing
the role of offspring. 4849

Number Cube Key

YOUR TOSS FORKBIRD OFFSPRING
1 1-tined forkbird
2 2-tined forkbird
4 4-tined forkbird
3, 5, 6 same as parent forkbird

7. Record the new population of each type of forkbird in your
group in the next row in your data table.

8. Return all of the wild loops to the “forest floor” (tray or bin) to
simulate the growth of wild loops.

9. Repeat Steps 3–6 for nine more rounds to represent additional
generations, being sure to fill in your data table after each round.

10. Share your data with the class as directed by your teacher. As a
class, record the population of each type of forkbird over many
generations. Record the class data in your science notebook.

4489 NNGGLLSS33AB21

EVOLUTION  21

ACTIVITY 4  BATTLING BEAKS

11. Create a graph of the class totals of each type of forkbird over
many generations. Plot the data for all three types of forkbirds on
a single graph. Be sure to title your graph, label your axes, and
provide a key.5051

ANALYSIS

1. Look at your graph of the class results. 52
a. Describe what happened to the number of each type of fork-
bird over many generations.53
b. Which type of forkbird was the most successful? Explain how
the class data support this conclusion.5455

2. The forkbirds that you studied are a single species. Although
they look slightly different, they are part of a single interbreeding
population. Imagine that a change in the food supply occurred.56
a. As a result of heavy rains, the major source of forkbird food is
now soft berries, like blueberries. After many, many genera-
tions, how many types of forkbirds do you think will be in the
population? Explain your reasoning.57
b. As a result of a drought, the major source of forkbird food
is now sunflower seeds. After many, many generations, how
many types of forkbirds do you think will be in the population?
Explain your reasoning.58

3. In this activity, mutations were introduced. Consider the effects of
the mutations on your forkbirds. Classify each mutation as bene-
ficial, neutral, or harmful. Explain your reasoning using evidence
from your investigation. 59

4. What are the strengths and weaknesses of the forkbird model for
explaining evolution by natural selection?6061

5. Using the forkbird model, explain the role of mutations in
changes in populations due to natural selection.6263646566676869

6565665565565656565694025331646702571988 MNNNNSNNNNNMENNNNSNNEELGGGGGGGGGGGGGGGAAWAASSSLSLLLCLLCPSCSRSSHPPPPPEPSSSSSSPCCCMEAAUDC4423336L66CPSXBBCBAABDDDA84EMMAFE12125242111211111211

22 EVOLUTION

BATTLING BEAKS  ACTIVITY 4

EXTENSION

If you were to conduct the activity with a 12-sided number cube
using the rules in the table below, what do you predict would be the
outcome?

Hint: Think about time.

Number Cube Key

YOUR TOSS FORKBIRD OFFSPRING
1 1-tined forkbird
2 2-tined forkbird
4 4-tined forkbird
3, 5, 6, 7, 8, 9, 10, 11, 12 same as parent forkbird

EVOLUTION  23



5 Mutations: Good or Bad?
modeling

In the previous activities, you explored how the environment
influences the selection of advantageous traits. These traits are
determined by bits of inherited genetic information called genes.
Humans have approximately 20,000 different genes, each one giving
rise to a product whose function influences your traits. The forkbirds
in the previous activity have a gene that determines the structure of
the beak. As you learned, variations in traits are sometimes caused
by a mutation (or a change to the sequence of a gene). If the mutation
leads to an advantageous trait, the mutation can be considered bene-
ficial. Other times, the mutation may have a negative effect or no
effect at all. Sometimes, whether a mutation is beneficial, harmful,
or neutral depends on the environment. You observed with the fork-
birds that the best beak shape depended on the food sources in the
environment.70

In this activity, you will investigate how natural selection affects
the presence of mutations in a human population.You and your
classmates will model a community in a remote part of sub-Saharan
Africa. As a class, you will investigate how a mutation could be bene-
ficial, harmful, or neutral to your family and the community.71

GUIDING QUESTION

How do mutations affect survival?

7701 NNGGLLSS44CB21

Are these color mutations
beneficial, harmful, or neutral?

EVOLUTION  25

ACTIVITY 5  MUTATIONS: GOOD OR BAD?

MATERIALS

For the class
34 hemoglobin plastic disks

For each student
1 First Generation Profile Card
1 First Generation Survivor Profile Card
1 Student Sheet 5.1, “Hemoglobin Mutations and Natural Selection”
1 Student Sheet 5.2, “Hemoglobin and Red Blood Cells Storyboard”

PROCEDURE

Part A: Generation One—The Initial Population
1. Read the background information in the box about hemoglobin

and sickle cell anemia. 727374

Background Information—
Hemoglobin and Sickle Cell Anemia

Hemoglobin is a protein inside all red blood cells. This protein gives the
red blood cells their color. Hemoglobin’s function is to carry oxygen to cells
throughout the body. Some people have a mutation in the hemoglobin gene
that gives rise to an altered protein called hemoglobin S. Hemoglobin S has
an abnormal structure that causes the mutated hemoglobin proteins to stick
together in chain-like structures. These chains of hemoglobin S cause normal
disc-shaped red blood cells to curve into sickle shapes as shown below on the
right, next to a normal red blood cell. These rigid sickle cells can clump and
block the normal function and flow of blood through the body.

777234 NNNGGGCCLSCC3CSAFE112

26 EVOLUTION

MUTATIONS: GOOD OR BAD? ACTIVITY 5

As shown in the map below, the hemoglobin S mutation is most common
in sub-Saharan Africa, Mediterranean countries, the Middle East, and India,
although it may occur anywhere.
Frequency of Hemoglobin S Mutation

Hemoglobin S frequency
0.1–0.2% 0.03–0.09%

In all of our cells, theFLriagebuAraeidr:sEevSoEtP3wUe PSoBIAc5P_oS3pEvioelustioonf3eeach gene, one from the biolog-
ical mother and oneMfyrroiamdProthReeg b9.5io/1l1ogical father. Worldwide, the majority of
people have two normal hemoglobin genes. This can be represented by the
letters HH, where the uppercase H represents a normal copy of the hemo-
globin gene. If a person inherits one mutated copy of the hemoglobin gene,
they are referred to as a sickle cell carrier. This can be noted as Hh, where the
lowercase h represents the mutated hemoglobin S gene. In these carriers,
half of their hemoglobin protein structure is normal and half is abnormal.
The abnormal hemoglobin protein structures can stick together, but since
the other half of their hemoglobin is normal, the chains are not long enough
to cause the cells to form sickle shapes. The cell structure still allows it to
function normally and carry oxygen.

If a person inherits two mutated copies of the gene, they are said to have
sickle cell anemia, and their genes are represented as hh.

GENES RED BLOOD CELL TRAIT
HH normal
Hh sickle cell carrier
hh sickle cell anemia

EVOLUTION 27

ACTIVITY 5  MUTATIONS: GOOD OR BAD?

2. Obtain a First Generation Profile Card from your teacher, and
read the information on the card. Note your red blood cell
traitare you Normal, are you a Sickle Cell Carrier, or do you
have Sickle Cell Anemiaand what your blood cell structure
looks like.

3. Record the numbers of individuals in your class with each trait
in the “Beginning population” column in the “Class Data” table
for Part A on Student Sheet 5.1, “Hemoglobin Mutations and
Natural Selection.”

4. In the remote sub-Saharan African region where your community
settled, there is no access to resources such as health care. There is
also a high incidence of malaria in this region. Read the following
information to learn more about malaria:

Malaria is a disease caused by a parasite that Over time, your red blood cells rupture, leading
infects your red blood cells. The parasite is to blood loss and release of the parasite into your
introduced into your body when a mosquito body. People that get malaria become very sick
carrying the parasite bites you. Inside your red with high fevers, shaking chills, and flu-like symp-
blood cells, the parasite multiplies to further toms. If not promptly treated, malaria may lead
infect more red blood cells. The parasite can also to death. The map below indicates where in the
travel throughout your body, since your blood world malaria is transmitted.
is constantly flowing to all of your body parts.

Global Transmission of Malaria

malaria transmission malaria transmission
occurs throughout occurs in some parts

28 EVOLUTION

LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e SB 5_4

MUTATIONS: GOOD OR BAD?  ACTIVITY 5

5. Follow your teacher’s instructions to determine the numbers of EVOLUTION  29
individuals that survive the malaria outbreak in your community.

• Almost all of sickle cell anemic individuals do not survive to
reproductive age due to lack of diagnosis or treatment of the
sickle cell disease.

• Normal individuals have a 50% chance of surviving malaria.

• Sickle cell carriers have an 80% chance of surviving malaria.

6. Record the number of surviving individuals in the table on your
Student Sheet.

Part B: The Next Generation

7. The individuals that survived malaria grew up and partnered
with individuals from a neighboring community. Obtain a new
First Generation Survivor Profile Card from your teacher.

8. Your profile card has an assigned letter and number (example:
A1 or A2). Find your partner with the same letter on their
Profile Card so that A1 is partnered with A2, B1 is partnered
with B2, etc.

9. Obtain an HH, Hh, or hh hemoglobin plastic disk from your
teacher, that matches your hemoglobin genes.Toss the disk (like
you would toss a coin) to determine which version of your two
genes you will pass on to each offspring.You will do this five times.
Record the genes each of you pass to your first five offspring in the
“Your Data” table on Part B on your Student Sheet.

10. Record the numbers of offspring in your class with each trait in
the “Beginning population” column of the “Class Data” table on
Part B on your Student Sheet.

11. Follow your teacher’s instructions to determine the numbers of
offspring that survive the malaria outbreak in your community,
and record these values on your Student Sheet.

12. Make two bar graphs with your data for Generation 2: one
showing the starting population and one showing the surviving
population. Alternatively, you can combine both sets of data into
one bar graph. Be sure to title your graph(s), label your axes, and
provide a key. 75

Hint: If you choose to make two graphs, consider making the
scale of both graphs the same because you will be comparing
them to each other.

75 NGSPUM1

ACTIVITY 5  MUTATIONS: GOOD OR BAD?

ANALYSIS

1. Look at the numbers of individuals you recorded on Student
Sheet 5.1 and the bar graph(s) you created. Compare the number
of individuals with each trait in the beginning population to the
surviving numbers. What patterns do you notice?767778

2. In your community, half of the normal and all of the sickle cell
anemic individuals died. Explain how normal and sickle cell
anemic offspring were born in the second generation.79

Hint: Remember that you have two copies of each gene, one from
each parent.

3. Use Student Sheet 5.2, “Hemoglobin and Red Blood Cells
Storyboard,” to develop a model to explain the relationship between
a mutation in a gene and the structure and function of an organism. 808182
• Be sure to include the genes, the protein, the red blood cell, and
the organism in all three cases—a normal individual, a carrier,
and a person with sickle cell anemia.
• Follow your teacher’s instructions for how to represent the
genes, protein, red blood cell, and organism.

4. Hemoglobin S is caused by a single mutation in the hemoglobin
gene. Explain how the environment affects whether this mutation
is beneficial, harmful, or neutral for a person. Use evidence from
your investigation to support your explanation. 83

5. Compare the “Frequency of Hemoglobin S Mutation” and
“Global Transmission of Malaria” maps seen earlier in this
activity. What is the evidence for a cause-and-effect relationship
between the frequency of malaria and the frequency of the hemo-
globin mutation?84

787888787378214906 SNNMNNMNNEGGGGGGAAASLPSCCSRSPPEPSPCCMDC36L6CPABDA3EMAE511121221

30 EVOLUTION

6 Mutations and Evolution
computer simulation

By now you know that some traits are more advantageous than
others in certain environments. Variations in traits result from
mutations. Over time, the frequency of variations in a population can
change. This change in trait frequency resulting from natural selec-
tion is central to the process of evolution. 8586

In this activity, you will continue studying the community in
sub-Saharan Africa that you began investigating in the last activity.
You will use a computer simulation to predict and analyze how trait
frequency changes in your population when there is a change in
the environment, such as improvements in health care or decreased
levels of malaria.

GUIDING QUESTION

Why does sickle cell trait frequency vary across the world?

8856 NNGGLLSS44BC11

Plasmodium infecting red blood cells

EVOLUTION  31

ACTIVITY 6  MUTATIONS AND EVOLUTION

Sickle Cell Simulation

In the “Mutations: Good or Bad?” activity, you started a community in a
remote part of sub-Saharan Africa and followed the sickle cell trait through
two generations. Now you will first examine up to 30 generations of your
community in the same environment. Then you will investigate how
changes in the environment are likely to affect your population. These
changes could include resources that help maintain health, such as building
health clinics in your region or investing in better pest control to minimize
the mosquito population.

MATERIALS8788

For each pair of students
computer with Internet access

PROCEDURE

Part A: Simulating More Generations
1. Visit the SEPUP Third Edition Evolution page of the SEPUP

website at www.sepuplhs.org/middle/third-edition and go to the sickle
cell simulation.

2. Set the variables to match your community from the previous
activity.89

a. Percent chance of getting malaria: This is the percentage
chance for each individual of getting malaria, or the incidence
rate. The available choices are 0, 25, 50, 75, or 100%. In your
community, the chance of getting malaria is 100%.

b. How good is the health care: This is the level of health care and
resources available. Three levels are available: no health care,
ok health care, or great health care.Your community has no
health care.

3. Press “Run Simulation.” The simulation will generate two graphs
with your results.

• Graph 1: This bar graph shows how many children survived to
adulthood and reproduced in each generation. This graph is
similar to the graph you produced in the last activity.

• Graph 2: This line graph shows the percentage of each trait in
the population for each generation over time.

888789 NNNGGGLSLPSSU33BAM211

32 EVOLUTION

MUTATIONS AND EVOLUTION  ACTIVITY 6

4. Record your results and any additional data or observations in EVOLUTION  33
your science notebook. Be sure to note any questions you have
that you would like to test.90

5. Answer Analysis item 1 in your science notebook.

Part B: Changing Environments

6. Now use the simulation to test how changing the environment
affects the frequency of the sickle cell trait in your population.
Change the variables to alter the percent chance of getting
malaria or the quality of health care.

Hint: Change one variable at a time.

a. Record your variables and the results in your science
notebook.

b. Write down any other questions that you would like to test.
c. Continue to do this until you can explain the cause-and-effect

relationship between the variable and the frequency of sickle
cell carriers in the population.

ANALYSIS

1. Use the data you collected or observations you made about the
environment to complete the following:9192

a. Use a mathematical representation, like a ratio or percent, to
explain what happened to the frequency of the sickle cell trait
over time when the chance of getting malaria was high and
there was no health care. 9394

b. Is there a cause-and-effect relationship? If so, describe that
relationship. If not, explain why not.95

2. Explain how environmental changes affect the sickle cell trait
over time in your population. Use evidence, including mathe-
matical representations, from your investigation to support your
explanation.96979899

3. Explain why the frequency of sickle cell trait is so much higher
in sub-Saharan Africa than in most other parts of the world.

4. What do you think would happen to the sickle cell trait in an
environment with no malaria and increased resources? Explain
your prediction.

99999999995912360847 NNMNMNNNNSEGGGGGGGAAACCPSSCCRSSPPEPPCCCCEUC6L6SPPCXBA4EMAAFE1561212221



7 Origins of Species
view and reflect

So far, you have seen how natural selection leads to evolutionary
changes within a species over time. For example, when a food
source that a bird species eats becomes scarce, any bird with a muta-
tion (for example, a particular beak shape) that allows it to feed on a
more common food source will have an advantage. These individuals
are more likely to survive and pass on the trait for this different beak
shape to their offspring. Over time, the percentage of the population
with this different beak shape will increase. But what happens when
this change occurs over hundreds or thousands of generations?

GUIDING QUESTION 100

How do new species evolve?

100 NGLS4C1

Caribbean Venezuela
Sea

Guyana

Colombia

Equator Ecuador Brazil
Galapagos

Islands

Peru

Paci c Ocean Bolivia

A Galapagos finch The Galapagos Islands 1,400 km from the coast of South America

LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e SB 7_2
MyriadPro Reg 9.5/11

EVOLUTION  35

ACTIVITY 7  ORIGINS OF SPECIES

MATERIALS

For each student
1 Student Sheet 7.1, “Viewing Guide: Galapagos Finch Evolution”

PROCEDURE

1. To prepare to watch the video on Galapagos finch evolution, first
read through Student Sheet 7.1, “Viewing Guide: Galapagos
Finch Evolution.”

2. Watch the story of Galapagos finch evolution.101

3. Complete Student Sheet 7.1.

ANALYSIS

1. Explain how environmental factors, genetic variation, and natural
selection resulted in the evolution of the 13 Galapagos finch
species observed today, when originally there was just one finch
species on the islands.102103104105106107108109

2. Do you predict that the same 13 finch species that exist today in
the Galapagos Islands will exist in 1 million years? Explain. 110111

Evolutionary Tree for Galapagos Finches small ground
mainland medium ground
large ground
cactus
large cactus
sharp-beaked ground
small tree
large tree
medium tree
mangrove
woodpecker
vegetarian
warbler

111111111111000100000071625841309 LMFiagyburAiraENNNNENSNNNeiELLddGGGGGGGGWA:RLLLLCLCSPsSSEHPSSSSSCCE6rC34444vS68PCXoACBAB8E9AoEE1212121212RP3eUegPSB9IA.75P_/S131Evolution 3e

36 EVOLUTION

ORIGINS OF SPECIES  ACTIVITY 7

3. How does the “Evolutionary Tree for Galapagos Finches” figure
represent the evolution of the 13 species?112

4. What qualities do you think Peter and Rosemary Grant have that
led to their becoming successful scientists?113

EXTENSION 1

Visit the SEPUP Third Edition Evolution page of the SEPUP website
at www.sepuplhs.org/middle/third-edition and watch the Evolution in
Action in Salamanders video. Reflect on whether you think these sala-
manders are becoming different species.

EXTENSION 2

Visit the SEPUP Third Edition Evolution page of the SEPUP website
at www.sepuplhs.org/middle/third-edition and go to the Grant Data link
to examine the actual data collected by the Grants on the medium
ground finch. Other than beak size, did the birds that survived the
1977 drought show any other differences from the birds that didn’t
survive? If you detect any other patterns, what might be the cause of
those patterns? If not, why do you think there was no relationship?

111132 NNGGCCCCPCAO21

EVOLUTION  37



8 History and Diversity of Life
reading

In the previous activity, you learned how new finch species evolved
over 3 million years on the Galapagos Islands. But the finches
are just one small branch of the tree of life. Earth is large and over
4 billion years old! How many different species have evolved on
Earth? Are they all still present today?

GUIDING QUESTION

How are the diverse species living today related to each other
and to the species that once lived on Earth?

Just a few of the 350,000 beetle species

EVOLUTION  39