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.
7. Complete the graphic organizer by listing three ways that species vary. For each pattern of biodiversity, list an example that Darwin observed.
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.
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?
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.
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
Contribution to Darwin’s Theory
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.
Lyell argued that the process