1. Today’s Agenda… Bellringer: 5 MC on Physical Science – Motion and Forces Take up HW Notes on Darwin’s Voyage SP#1 Homework

2. Today’s Targets… I can explain how and why species adapt to their environment. I can explain how natural selection accounts for the diversity of species.

3. Darwin’s Observations Living things are very diverse There are over 1.7 million species of organisms A species is a group of similar organisms that can mate with each other and produce offspring Characteristics of species are inherited as genetic information is passed from parent to offspring

4. Darwin’s Observations Darwin saw many unusual organisms on the Galapagos Islands Giant land turtles Seals covered with fur Lizards that ate cactus plants

5. Darwin’s Observations Many of the animals on the island were similar to animals on the mainland, but had important differences

6. Darwin’s Observations Darwin concluded that the animals had came from the mainland, reproduced, and became different from their relatives There were even differences between species as he traveled from one island to the next Example: the shells of tortoises, finch beaks

7. Adaptations Page 336 Figure 3 Finches on the Galapagos Islands Varied sizes and shapes of beaks Each species was well suited to the life it led Finches that ate nuts and seeds had strong, wide beaks Finches that ate insects had long, slender beaks

8. Adaptations Beak shape is an example of an adaptation Adaptation: a trait that helps an organism survive to reproduce and pass on its traits

9. Evolution Darwin continues to think about his research He concluded that animals on the island were faced with different conditions than they had been on the mainland Darwin thought the species gradually changed over many generations and became better adapted to new conditions Evolution is the gradual change of species over time Darwin wasn’t sure how this process had occurred, so he looked at more examples

10. Evolution Darwin considered the process of selective breeding to create offspring with certain traits What is selective breeding? Darwin proposed that a process similar to selective breeding must occur in nature But why were certain traits selected and how?

11. Natural Selection Darwin’s explanation for how evolution occurs Explained in his book The Origin of Species The process by which individuals that are better suited to their environment are more likely to survive and reproduce than others

12. Natural Selection Factors that affect natural selection: Overproduction Competition Variation

13. Natural Selection Overproduction Species produce more offspring than can survive There are not enough resources – food, water, living space

14. Natural Selection Competition Since resources are limited, the offspring must compete to survive

15. Natural Selection Variations Any difference between individuals of the same species

16. Natural Selection Some variations make certain individuals better adapted to the environment More likely to survive and then reproduce Offspring inherit the helpful trait and pass it on to their offspring Page 338, Figure 4

17. Natural Selection The environment has “selected” organisms with helpful traits to act as parents of the next generation Page 337 – Table 1 Applying Science

18. Natural Selection Over a long period of time, natural selection can lead to evolution Helpful variations increase, while those that are not helpful disappear