1. Darwin’s Voyage - Darwin’s Theory
Charles Darwin sailed on the Beagle, from England to the Galápagos Islands.

2. Overproduction and Variation
- Darwin’s Theory
Overproduction and Variation
Natural selection is the process by which individuals who are better adapted to their environment are more likely to survive and reproduce than other members of the same species.

3. Competition and Selection
- Darwin’s Theory
Competition and Selection
Variations among turtles make some of them better able to survive. Turtles that survive to become adults will be able to reproduce.

4. Relating Cause and Effect
- Darwin’s Theory
Relating Cause and Effect
In a graphic organizer, identify factors that cause natural selection.
Causes
Overproduction: More offspring are produced than can survive.
Variations: Members of the same species differ.
Competition: Offspring compete for survival.
Effect
Natural Selection
Selection: Some variations make individuals better fit for survival.
Environmental Change: Changes can affect an individual’s survival.
Genes: Genes that help determine survival are passed from parent to offspring.

5. Homologous Structures
- Evidence of Evolution
Homologous Structures
The structure of the bones in a dolphin’s flipper, a bird’s wing, and a dog’s leg is similar. Homologous bones are shown in the same color.

6. A Branching Tree - Evidence of Evolution
This branching tree shows how scientists now think that raccoons, lesser pandas, giant pandas, and bears are related.

7. Kaibab and Abert’s Squirrels
- Evidence of Evolution
Kaibab and Abert’s Squirrels
These two kinds of squirrels have been isolated from one another for a long time. Eventually this isolation may result in two different species.

8. Identifying Supporting Evidence
- Evidence of Evolution
Identifying Supporting Evidence
Evidence consists of facts that can be confirmed by testing or observation. As you read, identify the evidence that supports the theory of evolution. Write the evidence in a graphic organizer like the one below.
Evidence
Fossils show that organisms that lived in the past were very different from organisms alive today.
Theory
Patterns of early development show that some different organisms look similar during their early stages.
Evolution
Similar body structures in different species show that the organisms shared a common ancestor.