Darwin’s Theory Section 7.1 (page 224)

1. Who was Charles Darwin? 2. Describe the trip he began in December 1831. 3. What was the name of the ship he sailed on.

4. Describe the route that the Beagle traveled.

I. Darwin’s observations (225) 5. What three important observations did Darwin make?

A. Diversity 6. How many different species of organisms are currently identified on earth?

B. Fossils 7. What is a fossil? 8. Why was Darwin puzzled by the remains he found that resembled a sloth?

II. Galapagos Organisms (226) 9. Where did the Beagle dock in 1835?

A. Comparisons to South American Organisms 10. What was the difference between the iguanas on the Galapagos Islands and on the mainland?

11. How did Darwin believe that the mainland animals reached the islands?

B. Comparisons among the Islands 12. What differences did Darwin notice between tortoises from different islands?

C. Adaptations 13. What beak type did the finch that ate insects have? that ate seeds have?

15. What is an adaptation? 16. Why would milkweed adapt to have a sour taste or be poisonous?

III. Evolution (228) Darwin’s Reasoning 17. What were Darwin’s reasonings concerning the Galapagos Islands? 18. What is evolution? 19. What is a scientific theory?

B. Selective Breeding 20. What is selective breeding? 21. What trait was selected for in pigeons?

IV. Natural Selection (229) 22. What book did Darwin write and what year was it published? 23. What is natural selection? 24. What three factors affect natural selection?

A. Overproduction 25. What was Malthus theory? 26. What resources are needed by living things?

B. Variations 27. What is a genetic variation?

C. Competition 28. Why do organisms need to compete? 29. List two reasons an insect may not survive.

D. Selection 30. If an individual is better adapted to its environment what is most likely to happen? 31. Can offspring inherit these beneficial traits?

What did Darwin propose?

E. Environmental Factors 33. Summarize the history of Biston betularia.

Biston bettularia history: Pre-industrial revolution England: Peppered moths were light in color and blended Well against the bark of light colored trees.

The Industrial Revolution sent smoke and ash into the air which coated the cities and forests of England. The light moths were very visible against the dirty trees…

Their predators were birds who could now easily see them and eat them…

Some moths had a genetic variation that made them a dark color… they blended in with the dirty trees and were better able to survive.

The number of light colored moths declined and the number of dark colored moths increased… until… pollution controls were enacted and the environment went back to its original pattern. Which color moth was then favored?

34. How did environmental factors affect the peppered moth’s color?

F. Genes and Natural Selection 35. What causes genetic variation? 36. What type of traits can be acted on by natural selection? The End!