Name KEY	   Class 	    Date 	

16.1 Darwin’s Voyage of Discovery
Darwin’s Epic Journey
1. On the map below find and label the Galápagos Islands.
For Questions #2–4, complete each statement by writing the correct word or words. Refer to the map on the previous page as needed.
2. Darwin spent most of his time exploring the continent of South America; he did not visit North America	, Asia	 , or Antartica	.
3. During Darwin’s time, geologists were suggesting that Earth was ancient and changed over time	.
4. Darwin’s work offers insight into the living world by showing organisms are constantly
Changing or evolving	.

Observations Aboard the Beagle
Use the drawings of the tortoises to answer Questions #5 and 6.

Isabela Island tortoise		Hood Island tortoise
5. What important information about the Galápagos Islands tortoises did Darwin learn?
Darwin learned that the shell shape of a tortoise could be used to identify the island it inhabited.	
6. Given its body structure, which tortoise above would require a habitat where food is easy to reach?
Because the Isabela Island tortoise has a short neck that restricts the movement of its head, it would require a habitat where food is easy to reach.	

Over Time

Globally

Locally

7. Complete the graphic organizer by listing three ways that species vary. For each pattern of biodiversity, list an example that Darwin observed.

Glyptodonts and armadillos

Rheas and ostriches

Galapagos
Tortoises

Species

8. When Darwin returned to England, he learned that the small brown birds he observed on the Galápagos Islands were all finches. They resembled South American finches. What hypothesis does this observation support?
The birds are descended from South American ancestors that traveled to the Galapagos Islands.  The species have changed over time as they adapted to particular niches on each island.	

	

16.2 Ideas That Shaped Darwin’s Thinking

Lamarck’s Evolutionary Hypotheses
Use the diagram to answer Questions #1–4.

1. According to Lamarck’s hypothesis, what occurs between steps 2 and 3 in the diagram above to make the crab’s claw grow larger?
The crab selectively uses its left claw more.  This increased use causes the claw to grow in size.	

2. Which step in the diagram above shows the inheritance of acquired traits as proposed by Lamarck?
Step 3 shows the inheritance of acquired traits by the young.	

3. How did Lamarck propose that species change over time?
Lamarck was one of the first to develop scientific hypotheses about evolution and to realize that organisms change over time.	

4. How would Lamarck have explained the length of a giraffe’s neck?
A giraffe could have acquired a long neck because it began to stretch its neck upward to reach higher and higher on trees to eat.  As the giraffe stretched towards leaves on higher branches, its neck would grow a little longer.  Giraffes could then pass on their long neck to their offspring who could further lengthen their necks during their lifetimes.	

Artificial Selection
5. How do humans affect artificial selection? What role does nature play?
Darwin stated that nature provides the variation among organisms, and humans select and breed for the variations they find useful or appealing	
	
6. What is another name for artificial selection?
Selective breeding	
7. Describe how you could use artificial selection to breed pigeons with large beaks.
Find pigeons that naturally have larger than normal beaks.  Mate these pigeons.  Repeat this process over several generations until you achieve the desired beak size.	

Apply the Big idea

8. Complete the table about scientists who contributed to the development of the theory of evolution.

Scientists Who Contributed to Darwin’s Theory of Evolution	
Scientist	Contribution to Darwin’s Theory	
James Hutton	Hutton argued that Earth is many millions of years old.  Knowing that Earth was very old convinced Darwin that there had been enough time for life to evolve.	
Charles Lyell	Lyell argued that the process that changed Earth in the past were the same as the processes that are still changing Earth in the present.  Knowing that Earth could change over time helped Darwin realize that life might change as well.	
Jean-Baptiste Lamarck	Lamarck was one of the first scientists to recognize that evolution has occurred and that organisms change to live more successfully in their environment.  His general ideas about evolution and adaptation influenced Darwin.	
Thomas Malthus	Malthus thought that if the human population continued to grow unchecked, it would run out of living space and food.  Darwin realized that this was true of all organisms, not just humans.	

16.3 Darwin Presents His Case
Evolution by Natural Selection
1. What does the phrase struggle for existence mean?
It means that members of a population compete regularly to obtain food, living space, and other necessities of life	
2. Why is camouflage considered an adaptation?
Camouflage is a heritable trait that can help an organism avoid predation and thereby increases the chances for survival.	
3. How does an animal’s level of fitness relate to its chances of survival and reproduction?
The higher an animal’s level of fitness in its particular environment, the better its chances for survival and reproduction.	
For Questions #4–6, write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true.
F - inherited	 4.  Natural selection acts on acquired traits.
true	 5.  Any inherited characteristic that increases an organism’s chance of survival is considered an adaptation.
F - fitness	 6.  Natural selection is the ability of an individual to survive and reproduce in its specific environment.
7.  Below is a partially completed flowchart that models how natural selection drives evolution. The missing steps are listed below, out of order, and lettered A–D. Write the letter of the missing step in a blank box in the flowchart.
A. Adaptations are passed on to the next generation.
B. The accumulation of adaptations may lead to the evolution of a new species.
C. These offspring have few or no offspring of their own.
D. Some offspring inherit traits that increase fitness (adaptations).

Some offspring inherit traits that decrease fitness.

Individuals in a population have many variations.

Over time, adaptations accumulate in a population.

D

A

C

B

Common Descent
For Questions# 8–13, complete each statement by writing the correct word or words.
8. Natural selection depends on the ability of organisms to reproduce	, which means to leave descendants.
9. Every organism alive today descended	 from ancestors who survived and reproduced.
10. Over many generations, adaptation could cause successful species to evolve	 into new species.
11. Common descent suggests that all species, living and extinct, are related	.
12. The principle that living species descend, with changes, from other species over time is referred to as descent with modification	.
13. The fossil record	 provides physical evidence of descent with modification over long periods of time.

Apply the Big idea

14. In the three boxes on the left, draw an example of natural selection that might occur in a population of frogs. Then, on the lines at right, describe each stage.

The Struggle for Existence

Sample answer:  A population of frogs has a large
number of offspring.  Only a small fraction of these
offspring will survive.

Variation and Adaption /Survival of the Fittest

Sample answer:  In this population of frogs, heritable
variation includes short tongues and long tongues.
Long tongues are an adaption: the frogs with long
tongues are able to catch more flies than frogs with
shot tongues.  Long tongued frogs eat more and so
survive and reproduce more often than short-
tongued frogs.	

Natural Selection

	Sample answer:  Long-tongued frogs become more
Common than short-tongued frogs in this population
over time because (1) more frogs are born than survive,
(2) individuals vary in tongue-length and tongue-length
is a heritable trait, and (3) long-tongued individuals
have a higher fitness in this particular environment.

16.4 Evidence of Evolution
Biogeography
For Questions #1–3, complete each statement by writing the correct word or words.
1. Biogeographers study where organisms live now and where they and their ancestorslived in the past.
2. When individuals from a mainland bird population immigrate to various islands, natural selection may result in closely related	, but different, island species. 
3. Distantly related organisms may be similar if they live in similar environments	.

4. What explains the distribution of finch species on the Galápagos Islands?
The finch species had descended with modification from a common mainland ancestor.	
5. What explains the existence of similar but unrelated species?
Such species evolved features in common because they were exposed to similar pressures of natural selection.	

Comparing Anatomy and Embryology
6. Complete the table about types of anatomical structures.

Types of Anatomical Structures	
Structure Type	Description	Example	
Homologous structures	Structures that are shared by related
species and that have been inherited
from a common ancestor	Mammalian leg and amphibian leg	
Analogous structure	Body parts that share common function, but
not structure
	Wing of a bee and wing of a bird	
Vestigial structure	Body parts in animals that are so reduced
in size that they are just vestiges, or traces,
of homologous structures in other species	Hipbones in dolphins	

For Questions #7–11, match the structure with the correct type. A structure type may be used 

Anatomical Structure
A	  7. bat wing and mouse arm
A	  8. reptile foot and bird foot
B	  9. dolphin fin and fish tail
C	  10. eyes on a blind cave fish
B	  11. snake tongue and dog nose

Use the illustration above of homologous structures to answer Questions #12–15.

12. How are the forelimbs similar?
The forelimbs have the same kinds of bones in approximately the same positions.	
	
13. How are the forelimbs different?
Sample answer:  The bat’s “finger bones” are elongated and form the structure of a wing, while the human phalanges are shorter and form the structure for finges.	
	
14. How are homologous structures such as forelimbs evidence for common descent?
The bones are noticeably similar in structure and arrangement.  It is, therefore, reasonable to assume that they are descended from a common ancestral form.	

15. How does the pattern of embryological development provide further evidence that organisms have descended from a common ancestor?
The early developmental stages of many vertebrates look very similar.  Therefore, it is reasonable to assume that vertebrates are decended from a common ancestor.	

Structure Type
A. homologous structure
B. analogous structure
C. vestigial structure
Genetics and Molecular Biology
For Questions #16–22, complete each statement by writing the correct word or words.
16. The science of genetics	 provides molecular evidence that supports evolutionary theory.
17. All living cells use DNA	 and RNA	 to code heritable information.
18. The universal genetic code is used by almost all organisms to direct protein synthesis	.
19. Proteins that are homologous	 share extensive structural and chemical similarities.
20. Cytochrome c is a protein used for cellular respiration	 in almost every living cell.
21. Homologous genes called Hox genes control timing and growth in embryos	.
22. Relatively minor changes in an organism’s genome can produce major changes in an organism’s structure	.

VISUAL ANALOGY

23. 		
The art shows how finch beaks are similar to certain kinds of hand tools. Suppose a finch fed on insects that burrowed into small holes on tree trunks. What type of tool do you think this finch’s beak would resemble? Explain your answer. 

Sample answer:  The finch’s beak might resemble a very thin probe that can reach into a small hole and skewer or grasp the insect.	

Apply the Big idea

24. Complete the concept map.

Evidence for Evolution

includes

Experiments that verify natural selection occurs in nature

The universal genetic code and homologous proteins and genes

Similarities in anatomical structures and embryological developent

The fossil record

The geographic distribution of living species

Chapter Vocabulary Review
Match the term with its definition.

Term
A	  1.  evolution
C	  2.  fossil
G	  3.  fitness
B	  4.  adaptation
D	  5.  natural selection
F	  6.  homologous structures
E	  7.  vestigial structures

Definition
A. Change over time
B. Inherited characteristic that increases an organism’s chance of survival
C. Preserved remains of an ancient organism
D. The process by which organisms with variations most suited to their environment survive and leave more offspring than others
E. Small structures with little or no function
F. Structures that develop from the same embryonic tissues but have different mature forms
G. Ability of an individual to survive and reproduce
	in a specific environment

Homologous structures.  These limbs evolved from the front limbs of a common ancestor.  If these animals had different origins, they would probably not share so many common structures.

Body parts that share common function, but not structure.

The use of selective breeding to produce organisms with certain desirable traits

The study of where organisms live now and where they and their ancestors lived in the past.