1. Evolution by Natural Selection

2. What is a species?
A group of similar organisms that can mate with each other and produce fertile offspring

3. What did Darwin notice on the Galapagos Islands?
Many of the plants and animals on the Galapagos were similar to organisms on mainland South America
However, there were also important differences between the organisms on the islands and those on the mainland
Look at figure 2 on page 174

4. What did Darwin conclude led to the differences between species?
After studying the different finches on the Galapagos Islands Darwin concluded that their different beak shape was due to an adaptation
Adaptation – A trait that helps an organism survive and reproduce

5. A. What types of things would bird number 1 eat?
C. 3?
4. 4?

6. Evolution – the gradual change in a species over time
What did Darwin start to believe was occurring amongst the different species?
Darwin thought the species gradually changed over many generations and became better adapted to the new conditions
Evolution – the gradual change in a species over time

7. Why was Darwin’s idea considered a scientific theory?
It was a well-tested concept that explains a wide range of observations

8. Think Pair Share
What did Darwin discover on his voyage to the Galapagos Islands that led to his theory of evolution?

9. Darwin and Alfred Russell eventually proposed an explanation for how evolution occurs in a book called what?
The Origin of Species
This book explained that evolution occurs by means of natural selection

10. What is Natural Selection?
The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species

11. What are the factors that affect the process of natural selection?
Overproduction
Competition
Variations
Selection

12. How does overproduction affect natural selection?
So many species are produced that there are not enough resources (food, water, and living space)

13. How does competition affect natural selection?
Since food and other resources are limited, the offspring must compete in order to survive

14. How do Variations affect natural selection?
Any difference between individuals of the same species is called a variation
Some variations of a species may provide an advantage over the other members of the species without the variation

15. Differentiate between adaptation and variation.
Think Pair Share
Differentiate between adaptation and variation.

16. How does the environment select which organisms survive?
Individuals that are better adapted to their environment are more likely to survive and reproduce passing on the helpful trait to the next generation
In effect, The environment “selects” those organisms with helpful traits to be the parents of the next generation

17. How is natural selection related to evolution?
Over a long period of time, natural selection can lead to evolution
Helpful variations gradually accumulate in a species, while unfavorable ones disappear

18. What role do genes “play” in evolution?
Darwin did not know anything about genes or mutations so he could not explain what caused the variations or how they were passed on
Only traits that are inherited, or controlled by genes, can be acted upon by natural selection

19. 3 Explain how natural selection leads to evolution.
Rate Yourself
4 Apply concepts of natural selection and evolution by creating a scenario that demonstrates the ideas
3 Explain how natural selection leads to evolution.
2 Describe how the evidence supports evolution.
1 Identify evidence for evolution.