Download population

Chapter 7
The Evolution of Living Things
Table of Contents
Section 1 Change over Time
Section 2 How Does Evolution Happen?
Section 3 Natural Selection in Action
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Objectives
• Identify two kinds of evidence that show that
organisms have evolved.
• Describe one pathway through which a modern
whale could have evolved from an ancient mammal.
• Explain how comparing organisms can provide
evidence that they have ancestors in common.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Differences Among Organisms
• What Is a Species? A species is a group of
organisms that can mate with one another to produce
fertile offspring. A characteristic that helps an organism
survive and reproduce in its environment is called an
adaptation.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Differences Among Organisms, continued
• Do Species Change
over Time? Scientists
observe that species have
changed over time. The
process in which
populations gradually
change over time is called
evolution.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Evidence of Change over Time
• Fossils Sometimes, the remains or imprints of onceliving organisms are found in the layers of rock. These
remains are called fossils.
• The Fossil Record By studying fossils, scientists
have made a timeline of life that is known as the fossil
record. The fossil record organizes fossils by their
estimated ages and physical similarities.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Evidence of Ancestry
• Order of Life The fossil record provides evidence
about the order in which species have existed.
• Drawing Connections Scientists have named and
described hundreds of thousands of living and ancient
species. Scientists use information about these
species to sketch out a “ tree of life” that includes all
known organisms.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Examining Organisms
• Case Study: Evolution of the Whale Scientists
think that the ancient ancestor of whales was probably
a mammal that lived on land and that could run on four
legs.
• Walking Whales The organisms shown on the next
slide form a sequence between ancient four-legged
mammals and modern whales. Several pieces of
evidence indicate that these species are related by
ancestry.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Comparing Organisms
• Comparing Skeletal Structures The structure and
order of bones of a human arm are similar to those of
the front limbs of a cat, a dolphin, and a bat. These
similarities suggest that cats, dolphins, bats, and
humans had a common ancestor.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Comparing Organisms, continued
• Comparing DNA Scientists find that species that
have many traits in common do have similarities in
their DNA.
• The fact that all existing species have DNA
supports the theory that all species share a common
ancestor.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Objectives
• List four sources of Charles Darwin’s ideas about
evolution.
• Describe the four parts of Darwin’s theory of
evolution by natural that gradual processes had
changed the Earth’s surface over selection.
• Relate genetics to evolution.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Charles Darwin
• Darwin’s Excellent Adventure After Charles
Darwin graduated from college, he served as
naturalist on a ship called the HMS Beagle. During a
voyage around the world, Darwin collected thousands
of plant and animal samples.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Charles Darwin
• Darwin’s Finches Darwin noticed that the finches
of the Galápagos Islands were a little different from
the finches in Ecuador. And the finches on each island
differed from the finches on the other islands.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Darwin’s Thinking
• Ideas About Breeding The process in which humans
select which plants or animals to reproduce based on
certain desired traits is called selective breeding.
• Ideas About Population Only a limited number of
individuals survive to reproduce. Thus, there is
something special about the offspring of the survivors.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Darwin’s Thinking, continued
• Ideas About Earth’s History Darwin had begun to
think that species could evolve over time. It became
clear to Darwin that Earth was much older than
anyone had imagined.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Darwin’s Theory of Natural Selection
• What Is Natural Selection? Darwin proposed the
theory that evolution happens through a process that he
called natural selection. Individuals that are better
adapted to their environment survive and reproduce
more successfully than less well adapted individuals.
• Genetics and Evolution Today, scientists have found
most of the evidence that Darwin lacked. They know that
variation happens as a result of differences in genes.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Objectives
• Give three examples of natural selection in action.
• Outline the process of speciation.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Changes in Populations
• Adaptation to Hunting People hunt elephants for
their tusks. As a result, fewer of the elephants that
have tusks survive to reproduce, and more of the
tuskless elephants survive.
• Insecticide Resistance Insecticides have been
used so much that now more than 500 kinds of insects
have developed resistance to certain insecticides.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Changes in Populations, continued
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Changes in Populations, continued
• Competition for Mates Many species have so
much competition for mates that interesting
adaptations result. For example, the females of many
bird species prefer to mate with males that have
colorful feathers.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Forming a New Species
• Sometimes, drastic changes that can form a new
species take place. The formation of a new species
as a result of evolution is called speciation.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Forming a New Species, continued
• Separation Speciation often begins when a part of a
population becomes separated from the rest.
• Adaptation Populations constantly undergo natural
selection. After two groups have separated, natural
selection may act on each group in different ways.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Forming a New Species, continued
• Division Over many
generations, two
separated groups of a
population may become
very different until the
point when they can no
longer mate with one
another. At this point, the
two groups are no longer
the same species.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
The Evolution of Living Things
Concept Map
Use the terms below to complete the concept map on
the next slide.
evolution
evidence
extinct species
living species
common ancestors
DNA
time
fossil record
body structures
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Concept Map
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Concept Map
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Reading
Read each of the passages. Then, answer the questions
that follow each passage.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Passage 1 When the Grand Canyon was forming, a
single population of tassel-eared squirrels may have
been separated into two groups. Today, descendants of
the two groups live on opposite sides of the canyon. The
two groups share many characteristics, but they do not
look the same. For example, both groups have tasseled
ears, but each group has a unique fur color pattern. An
important difference between the groups is that the
Abert squirrels live on the south rim of the canyon, and
the Kaibab squirrels live on the north rim.
Continued on the next slide
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Passage 1, continued
The environments on the two sides of the Grand
Canyon are different. The north rim is about 370 m
higher than the south rim. Almost twice as much
precipitation falls on the north rim than on the south rim
every year. Over many generations, the two groups of
squirrels have adapted to their new environments. Over
time, the groups became very different. Many scientists
think that the two types of squirrels are no longer the
same species. The development of these two squirrel
groups is an example of speciation in progress.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
1. Which of the following statements best describes the
main idea of this passage?
A Speciation is evident in two groups of squirrels in the
Grand Canyon area.
B Two groups of squirrels in the Grand Canyon area are
closely related.
C Two species can form from one species. This process
is called speciation.
D There are two groups of squirrels because the Grand
Canyon has two sides.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
1. Which of the following statements best describes the
main idea of this passage?
A Speciation is evident in two groups of squirrels in the
Grand Canyon area.
B Two groups of squirrels in the Grand Canyon area are
closely related.
C Two species can form from one species. This process
is called speciation.
D There are two groups of squirrels because the Grand
Canyon has two sides.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. Which of the following statements about the two types
of squirrels is true?
F They look the same.
G They live in similar environments.
H They have tasseled ears.
I They can interbreed with each other.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. Which of the following statements about the two types
of squirrels is true?
F They look the same.
G They live in similar environments.
H They have tasseled ears.
I They can interbreed with each other.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Passage 2 You know from experience that individuals
in a population are not exactly the same. If you look
around the room, you will see a lot of differences
among your classmates. You may have even noticed
that no two dogs or two cats are exactly the same. No
two individuals have exactly the same adaptations. For
example, one cat may be better at catching mice, and
another is better at running away from dogs.
Continued on the next slide
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Passage 2, continued Observations such as these
form the basis of the theory of natural selection.
Because adaptations help organisms survive to
reproduce, the individuals that are better adapted to
their environment are more likely to pass their traits to
future generations.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
1. In the passage, what does population mean?
A a school
B some cats and dogs
C a group of the same type of organism
D a group of individuals that are the same
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
1. In the passage, what does population mean?
A a school
B some cats and dogs
C a group of the same type of organism
D a group of individuals that are the same
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. In this passage, which of the following are given as
examples of adaptations?
F differences among classmates
G differences among cats
H differences between cats and dogs
I differences among environments
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. In this passage, which of the following are given as
examples of adaptations?
F differences among classmates
G differences among cats
H differences between cats and dogs
I differences among environments
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
3. Which of the following statements about the
individuals in a population that survive to reproduce is
true?
A They have the same adaptations.
B They are likely to pass on adaptations to the next
generation.
C They form the basis of the theory of natural
selection.
D They are always better hunters.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
3. Which of the following statements about the
individuals in a population that survive to reproduce is
true?
A They have the same adaptations.
B They are likely to pass on adaptations to the next
generation.
C They form the basis of the theory of natural
selection.
D They are always better hunters.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Interpreting Graphics
The graph below shows average beak sizes of a group
of finches on one island over several years. Use the
graph to answer the questions that follow.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
1. In which of the years studied
was average beak size the
largest?
A 1977
B 1980
C 1982
D 1984
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
1. In which of the years studied
was average beak size the
largest?
A 1977
B 1980
C 1982
D 1984
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. If beak size in this group of
birds is linked to the amount of
rainfall, what can you infer about
the year 1976 on this island?
F The year 1976 was drier than
1977.
G The year 1976 was drier than
1980.
H The year 1976 was wetter than
1977.
I The year 1976 was wetter than
1984.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. If beak size in this group of
birds is linked to the amount of
rainfall, what can you infer about
the year 1976 on this island?
F The year 1976 was drier than
1977.
G The year 1976 was drier than
1980.
H The year 1976 was wetter than
1977.
I The year 1976 was wetter than
1984.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
3. During which year(s) was
rainfall probably the lowest on
the island?
A 1978, 1980, and 1982
B 1977, 1980, 1982, and 1984
C 1982
D 1984
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
3. During which year(s) was
rainfall probably the lowest on
the island?
A 1978, 1980, and 1982
B 1977, 1980, 1982, and 1984
C 1982
D 1984
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
4. Which of the following statements best summarizes
this data?
F Average beak size stayed about the same except
during wet years.
G Average beak size decreased during dry years and
increased during wet years.
H Average beak size increased during dry years and
decreased during wet years.
I Average beak size changed randomly.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
4. Which of the following statements best summarizes
this data?
F Average beak size stayed about the same except
during wet years.
G Average beak size decreased during dry years and
increased during wet years.
H Average beak size increased during dry years and
decreased during wet years.
I Average beak size changed randomly.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Math
Read each question, and choose the best answer.
Average Beak Measurements of Birds
of the Colores Islands
Island
Ave. beak
Ave. beak No. of unique
length (mm) width (mm)
species
Verde
9.7
6.5
5
Azul
8.9
8.7
15
Rosa
5.2
8.0
10
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Standardized Test Preparation
Chapter 7
1. What is the ratio of the number of species on Verde
Island to the total number of species on all three of the
Colores Islands?
A 1:2
B 1:5
C 1:6
D 5:15
Average Beak Measurements of Birds
of the Colores Islands
Island
Ave. beak
Ave. beak No. of unique
length (mm) width (mm)
species
Verde
9.7
6.5
5
Azul
8.9
8.7
15
Rosa
5.2
8.0
10
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Standardized Test Preparation
Chapter 7
1. What is the ratio of the number of species on Verde
Island to the total number of species on all three of the
Colores Islands?
A 1:2
B 1:5
C 1:6
D 5:15
Average Beak Measurements of Birds
of the Colores Islands
Island
Ave. beak
Ave. beak No. of unique
length (mm) width (mm)
species
Verde
9.7
6.5
5
Azul
8.9
8.7
15
Rosa
5.2
8.0
10
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. What percentage of all bird species on the Colores
Islands are on Rosa Island?
F approximately 15%
Island
No. of unique
species
Verde
5
Azul
15
Rosa
10
G approximately 30%
H approximately 50%
I approximately 80%
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
2. What percentage of all bird species on the Colores
Islands are on Rosa Island?
F approximately 15%
Island
No. of unique
species
Verde
5
Azul
15
Rosa
10
G approximately 30%
H approximately 50%
I approximately 80%
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
3. On which of the islands is the ratio of average beak
length to average beak width closest to 1:1?
A Verde Island
Island
B Azul Island
C Rosa Island
Ave. beak
Ave. beak
length (mm) width (mm)
Verde
9.7
6.5
Azul
8.9
8.7
5.2
8.0
D There is not enough Rosa
information to determine
the answer.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
3. On which of the islands is the ratio of average beak
length to average beak width closest to 1:1?
A Verde Island
Island
B Azul Island
C Rosa Island
Ave. beak
Ave. beak
length (mm) width (mm)
Verde
9.7
6.5
Azul
8.9
8.7
5.2
8.0
D There is not enough Rosa
information to determine
the answer.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
4. On which island does the bird with the smallest beak
length live?
F Verde Island
Island
G Azul Island
H Rosa Island
Ave. beak
Ave. beak
length (mm) width (mm)
Verde
9.7
6.5
Azul
8.9
8.7
5.2
8.0
I There is not enough Rosa
information to determine
the answer.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
4. On which island does the bird with the smallest beak
length live?
F Verde Island
Island
G Azul Island
H Rosa Island
Ave. beak
Ave. beak
length (mm) width (mm)
Verde
9.7
6.5
Azul
8.9
8.7
5.2
8.0
I There is not enough Rosa
information to determine
the answer.
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 1 Change over Time
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 2 How Does Evolution Happen?
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Section 3 Natural Selection in Action
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Chapter 7
Standardized Test Preparation
Chapter menu
Resources
Copyright © by Holt, Rinehart and Winston. All rights reserved.