Download Evidence for evolution

Evidence for evolution
Grades 9-10
Evidence for evolution
Teacher’s Guide
Teacher’s Guide
Introduction
Thank you for using one of the Honolulu Zoo Society’s educational worksheets. This teacher’s
guide is meant to help you direct your students through the Evidence for Evolution worksheet if
needed. The worksheet is designed for students in grade 9-10, and addresses the following
grade 9-12 State Science Standards:
Unity and Diversity
• Explain and justify the scientific classification system.
Biological Evolution
• Explain how molecular and anatomical evidences substantiate the theory of evolution.
• Explain the basic idea of biological evolution.
In keeping with current research on worksheets and free choice learning, the tasks on this
worksheet mainly require observations of the animals and their behavior, but also some labelreading. The worksheet is a work in progress, though, and any suggestions or insights you have
are very welcome!
The following map of the Zoo will help you guide your students to the starting point for their
worksheet tasks at the nēnē exhibit.
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Evidence for evolution
Teacher’s Guide
Glossary
ANCESTOR: An individual from whom a person or an animal is descended, a forefather.
AQUATIC: Growing or living in water.
CHARACTERISTIC: A distinguishing trait, quality, or property.
EVOLUTION: The historical development of a biological group (species). A theory that the various
types of animals (or other organisms) have their origin in preexisting types of animals (or other
organisms) and that the distinguishable differences are due to modifications in successive generations.
EVOLUTION, CONVERGENT: When the process of evolution causes two unrelated species to become more similar with regard to certain characteristics.
EVOLUTION, DIVERGENT: When the process of evolution causes two related species to become
more dissimilar with regard to certain characteristics.
GENERATION: A group of animals that constitute a single step in the line of descent from an ancestor.
MIGRATION: To move from one region or climate to another for breeding or feeding.
OFFSPRING: The young of an animal, children.
PRIMITIVE: At an early stage of development, an ancestral type.
REPRODUCTIVE AGE: Sexually mature age, at an age where individual is able to reproduce or
breed.
SELECTION: A process that results in the survival and reproduction of some individuals but not of
others. This has the result that the inherited characteristics of the survivors are perpetuated.
SELECTION, ARTIFICIAL: Human intervention in animal or plant reproduction to ensure that certain
desirable traits are represented in successive generations.
SELECTION, NATURAL: According to Darwin's theory of evolution, a natural process in which only
the organisms best adapted to their environment tend to survive and transmit their genetic characteristics in increasing numbers to succeeding generations while those less adapted tend to be
eliminated.
TERRESTRIAL: Growing or living on land.
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Evidence for evolution
Teacher’s Guide
Answer key
1. Which characteristics might these rat-catching dogs have had, in your opinion?
Answer: they were probably quick, aggressive, and small.
2. If the rat-catching dogs had the characteristics (speed, size, and temper) that you checked
off above, what would the consequences for their offspring be?
Answer:
5 The offspring would probably inherit those same characteristics
5
The offspring would probably be good rat-catchers
5
Humans might have taken extra care of the offspring because of their usefulness
3. What’s the difference between artificial selection and natural selection? Below, you’ll find
two scenarios. Indicate which one is natural selection, and which one describes artificial selection.
5 Artificial selection
F Natural selection
The individuals that
are best suited for survival are the ones that
most likely will live
long enough to reach
reproductive age. This
means that they are
the ones that get to
breed, and their characteristics (being good
survivors) are inherited by their offspring.
The individuals that
are allowed to breed
are chosen by humans These individuals have the characteristics that humans
are interested in. This
process
produces
animals that express
some characteristics,
such as a stubby
snout, very strongly.
F Artificial selection
5 Natural selection
4. Natural selection is a process that creates animals that are increasingly well adapted to their
environment and thus are good survivors. On the other hand, artificial selection produces
animals that… Check off the correct statement(s)
Answer:
5
Express a certain characteristic that humans prefer.
5
Are not necessarily better survivors in the wild than their ancestors.
5
Would probably not exist without human intervention.
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Evidence for evolution
Teacher’s Guide
5. Find the nēnē or Hawaiian goose exhibit. The ancestor of the nēnē is a fairly well known
goose species. Which species?
Answer: The Canada goose
6. The table lists some of the characteristics that differ between the ancestral goose and the
nēnē. Your job is to complete the table.
Answer (suggestion):
Characteristics
Body posture
(upright or horizontal)
Shape of feet
Length of neck
Wing size
Ancestral goose
Nēnē
Horizontal
Upright
Webbed
Webbing reduced, long
toes
Long
Relatively short
Long, strong
Shorter, less strong
7. Write in your own words how you think the nēnē characteristics were created by natural selection:
Answer (suggestion):
The nēnē lives on land, and rarely swims. The upright posture is
Nēnē posture better for walking. (The horizontal posture of a Canada goose is
better for swimming.)
The nēnē evolved with no land predators, so it never needed to
Shape of nēnē feet swim to escape. Instead, the webbing on its feet is reduced so the
long toes can grip uneven ground more easily.
Length of nēnē neck
The nēnē feeds on land plants. Unlike its ancestor, it doesn’t need
a long neck to be able to reach plants underwater.
The nēnē never leaves Hawai’i, and only flies short distances.
Nēnē wing size Over time, its wings have become shorter and less strong than its
ancestor’s.
8. Find the gharial exhibit. Gharials and dolphins give an interesting example of convergent
evolution. Which feature do gharials have in common with dolphins? (Hint: think about what
they eat!)
Answer: A long slender snout full of equally sized, cone-shaped teeth. This is an adaptation
for catching fish.
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Evidence for evolution
Teacher’s Guide
9. Do the following pairs of animals give examples of convergent or divergent evolution?
Convergent
Divergent
and
5
F
and
F
5
and
F
5
and
5
F
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Evidence for evolution
Student Worksheet
Student Worksheet
Did you know that all dog breeds originated from the same ancestor? The ancestor of modern
dogs was probably a wolf-like type of dog.
Wolf-like ancestor
Yorkshire
terrier
Golden retriever
Cocker
spaniel
Poodle
Most modern dog breeds, like the four shown above, have been created by humans. But how
were the breeds created? Consider this scenario:
The first primitive dogs were probably wolf-like animals that hung around human settlements to
find food scraps. But where there are human settlements, there are often also rats. At some
point, humans in these settlements probably noticed that some dogs were very skilled at catching rats.
1.
Which characteristics might these rat-catching dogs have had, in your opinion?
F Quick or F Slow
F Aggressive or F Docile
F Large or F Small
The humans in the settlements might have taken special care of these rat-catchers. They might
even have bred rat-catching female dogs with rat-catching male dogs.
2.
If the rat-catching dogs had the characteristics (speed, size, and temper) that you checked
off above, what would the consequences for their offspring be? Check off the correct statement(s)
F
The offspring would probably inherit those same characteristics
F
The offspring would probably be good rat-catchers
F
Humans might have taken extra care of the offspring because of their usefulness
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Evidence for evolution
Student Worksheet
Imagine what would happen if humans kept breeding rat-catchers with rat-catchers, generation
after generation. The end result would be a small, quick, aggressive type of dog, not because
humans wanted a small, quick, aggressive dog, but because they wanted a good rat-catcher,
and those are the characteristics of a good rat-catcher.
There are several examples of such rat-catchers today! Most terriers were
actually originally bred as rat-catchers, and if you’ve ever known a terrier,
you’ll know that they are indeed small, quick, and aggressive.
The process of crossing animals with certain characteristics with other
animals with those same characteristics is called selection. When humans
control the process, it is called artificial selection.
The process of selection happens in nature, too. In this case, it is called natural selection.
3.
What’s the difference between artificial selection and natural selection? Below, you’ll find
two scenarios. Indicate which one is natural selection, and which one describes artificial selection.
F Artificial selection
F Natural selection
4.
The individuals that
are best suited for survival are the ones that
most likely will live
long enough to reach
reproductive age. This
means that they are
the ones that get to
breed, and their characteristics (being good
survivors) are inherited by their offspring.
The individuals that
are allowed to breed
are chosen by humans These individuals have the characteristics that humans
are interested in. This
process
produces
animals that express
some characteristics,
such as a stubby
snout, very strongly.
F Artificial selection
F Natural selection
Natural selection is a process that creates animals that are increasingly well adapted to
their environment and thus are good survivors. On the other hand, artificial selection produces animals that… Check off the correct statement(s)
F
Express a certain characteristic that humans prefer.
F
Are not necessarily better survivors in the wild than their ancestors.
F
Would probably not exist without human intervention.
Now, let’s look at some animals that have evolved through natural selection! Go to the next
page…
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Evidence for evolution
Student Worksheet
5.
Find the nēnē or Hawaiian
goose exhibit at the Zoo. The
ancestor of the nēnē is a fairly
well known goose species.
Which species?
Natural
selection
Î
Answer
Ancestor of nēnē
Nēnē
The ancestor of the nēnē was originally from North America. It arrived at the Hawaiian Islands
about 500,000 years ago. Since arriving here, the goose changed its appearance from the ancestral form to the present form: the nēnē. Let’s look closer at some of these changes!
6.
The table lists some of the characteristics that differ between the ancestral goose and the
nēnē. Your job is to complete the table.
Characteristics
Ancestral goose
Body posture
(upright or horizontal)
Length of legs
Webbing of feet
Length of neck
Wing size
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Nēnē
Evidence for evolution
Student Worksheet
Now, let’s think of how these changes came about. What caused this selection to happen?
Think about the different habitats the ancestor and the nēnē occupy, and the different behaviors
they have as a result of this.
Ancestor
• Lives in marshes,
near water
• Feeds on aquatic
plants
• Has many terrestrial
predators
• Migrates over long
distances every year
7.
Nēnē
•
•
•
•
Lives on land
Feeds on terrestrial
plants
Had no terrestrial
predators for thousands of years
Migrates only over
very short distances
Write in your own words how you think the nēnē characteristics were created by natural selection:
Nēnē body posture
Length of nēnē legs
Webbing of nēnē feet
Length of nēnē neck
Nēnē wing size
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Evidence for evolution
Student Worksheet
When natural selection causes one animal species to split into two (or more) species in this
manner, it can be illustrated in the following way:
Canada
goose
Ancestral
species
(Canada
goose)
Nene
This process is called divergent evolution. To diverge means to become dissimilar or different,
so when natural selection causes two species to become more and more dissimilar (as with the
Canada goose and the nēnē), we call it divergent evolution.
Another process is called convergent evolution. When two species develop the same adaptation, even though they are not related to each other, they converge (become more similar).
8.
Find the gharial exhibit. Gharials and dolphins give an interesting example of convergent
evolution. Which feature do gharials have in common with dolphins? (Hint: think about
what they eat!)
Answer:
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Evidence for evolution
Student Worksheet
9.
Are the following pairs of animals examples of convergent or divergent evolution?
Convergent
Divergent
and
F
F
and
F
F
and
F
F
and
F
F
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