Darwin’s Theory of Evolution

1. Darwin’s Theory of Evolution Chapter 15

2. 15-1 Warm Up A Trip Around the World While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises. 1.On a sheet of paper, list five animals that you have encountered in the past two days. 2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.) 3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.

3. The Puzzle of Life’s Diversity • Biological Diversity – the variety of living things - describes the millions of different shapes, sizes & habitats on Earth • Evolutionary Theory – a possible answer to explain the diversity of living things - a collection of scientific facts, observations, and hypotheses.

4. Evolution • Change over time • The process by which modern organisms have descended from ancient organism

5. Theory • A well supported testable explanation of phenomena that have occurred in the natural world

6. Charles Darwin • Born in England on Feb. 12, 1809 (same day as A. Lincoln) • In 1831, he set sailed on the H.M.S Beagle for a trip around the world

7. Darwin’s Observations • Patterns of Diversity: 1. plants and animals seem remarkably well adapted to whatever environment they inhabit (live) 2. organisms have many different ways to survive & produce offspring 3. certain animals were only found on specific continents, even though other continents had similar environments .

8. Darwin’s Observations • Living Organisms and Fossils: 1. Darwin collected many fossils: - preserved remains of ancient organisms 2. he realized that some resembled living organisms and others looked completely unlike any other creature. 3. These fossils made Darwin wonder how so many species disappeared & if they were related to living things now

9. Charles Darwin

10. Warm Up • Timeline – Origins of Evolutionary Thought • pp. 374-375 • Construct a timeline using the information on the timeline in your book • Do not copy pictures, just the written information and dates

11. Galapagos Islands • Small group of islands located off S. America • Very different climates even though there are close together • Darwin used his observations from these islands to create his Theory of Evolution • He studied land tortoises & marine iguanas and observed differences between each island • Most importantly he studied birds called a Finch and observed and analyzed their differences in their beaks

12. Land Tortoises of the Galapagos Islands . Pinta Tower Marchena Pinta IslandIntermediate shell James Fernandina Santa Cruz Isabela Santa Fe Hood Island Saddle-backed shell Floreana Hood Isabela Island Dome-shaped shell

13. Land Tortoises

14. Land Iguana

15. Marine Iguanas

16. Marine Iguanas

17. Galapagos Islands from Space

18. H.M.S. Beagle

19. Finches

20. Finches

21. Finches

23. The Journey Home • Upon returning to England, Darwin thought about his observations & asked himself 3 very important questions: 1. Were the animals living on the different islands once members of the same species? 2. If they were, how did these species evolve after being separated onto the different islands? 3. If they did evolve (change) how did they do it?

24. Warm - Up My, How You’ve Changed! Prior to the 1800s, life scientists knew that living things changed over generations. They just didn’t know how these changes were brought about. 1. Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair. 2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument. 3. Which of the items in your lists do you think you might pass on to your children? Explain your answer.

26. Ideas that Shaped Darwin’s Thinking • Before Darwin’s time, most Europeans believed that Earth and all life forms: 1. were created only a few 1000 years ago 2. had not changed since creation • During Darwin’s life, a lot of evidence was discovered to change this way of thought • This made Darwin dramatically change his way of thinking.

27. An Ancient, Changing Earth • During the 18th and 19th centuries, scientists recognize: 1. Earth is millions of years old 2. processes that changed Earth in the past are the same processes that are happening today • James Hutton • Charles Lyell • Jean Baptiste Lamarck • Thomas Malthus

28. Scientists Who Influenced Darwin • In your notebook, create a table to show the scientists and their findings that influenced Darwin. Use pages 374-377 to find the information

29. CLASS ACTIVITY • Read “Hutton and Geological Change” on page 374. (1 paragraph) • List at least 4 beliefs of Hutton in your notebook. • 1. geological forces shaped the Earth. • 2. • 3. • 4. • 5. • You will have 5 minutes to finish!

30. James Hutton - 1795 • He believed: 1. geological forces have shaped Earth 2. Earth was made of layers of rocks that form very slowly 3. rocks move up by forces beneath the surface & others are buried & others are pushed up to make mountains 4. outer layer is shaped by natural forces – rain, wind, heat & cold temperatures 5. All of these processes operate extremely slow – over millions of years 6. Concluded that Earth is millions of years old

31. Movement of Earth’s Crust . Sea level Sea level As the surface erodes due to water, wind, waves, or glaciers, the older rock surface is exposed. Sedimentary rocks form in horizontal layers. New sediment is then deposited above the exposed older rock surface. When part of Earth’s crust is compressed, a bend in a rock forms, tilting the rock layers.

32. Scientists Who Influenced Darwin • In your notebook, create your own notes on the scientists and their findings that influenced Darwin. • Lyell – 5 main points (describe each one) • Lamarck – 3 main points (describe each one) • Malthus – 2 main points (describe each one) Use pages 375-377 to find the information

33. Charles Lyell • Wrote book called “Principles of Ecology” • Darwin read it when on the Beagle • He stressed that scientists must study past events to understand the events they are observing now • His work explained how geological features could be build up & broken down over long periods of time • It also helped Darwin understand how important geological phenomena is on the location and findings of fossils

34. Jean Baptiste Lamarck • French scientist who was one of the first to: 1. recognize that living things have changed over time 2. all species were descended from other species 3. organisms somehow adapted to their environments • Lamarck’s work was published in 1809, the same year Darwin was born

35. Lamarck’s Evolution Hypothesis • He proposed that by: 1. use or disuse of organs, organisms gained or lose certain traits during their lifetime. 2. These traits could then be passed on to their offspring 3. Over time, this process led to change in a species

36. Tendency Toward Perfection • Lamarck proposed that all organisms have an innate tendency toward complexity & perfection. • As a result, living things are always changing & acquiring new traits to help to adapt & survive

37. Use and Disuse • Lamarck proposed that organisms could change the shape and size of certain organs by using their bodies in new ways • If the organism used a new part of body, it would develop into a new structure • If the organism disused the part of body, it would decrease in size and over many generations disappear.

38. Inheritance of Acquired Traits • Lamarck thought that acquired characteristics could be inherited • Acquired Characteristics – traits you gain from your own experiences and training • Example – if you spent your life lifting weights to build your muscles, then your children would inherit big muscles too!

39. Evaluating Lamarck’s Hypothesis • Incorrect in many ways: 1. He did not know how traits are inherited 2. He did not know that an organism’s behavior has no effect on its inheritable characteristics ** Lamarck was the 1st to develop a hypothesis of evolution & to realize that organisms can adapt to their environment.**

40. Thomas Malthus • Important influence on Darwin • In 1798, Malthus published a book that stated: “If the human population continued to grow unchecked, sooner or later there would be insufficient living space & food for everyone” • He felt that the only forces that could fight against this were: war, famine, & disease

41. Darwin’s Thoughts on Malthus • He realized Malthus’ ideas applied to plants and animals even more • Because animals & plants can reproduce much faster & more numbers than humans • What Darwin did not realize at this time was: 1. majority of offspring die 2. only a few survive long enough to reproduce themselves ** Trying to figure out why the above occurs was the central idea behind his explanation of evolutionary change.**

42. Warm Up When Is a Flipper a Wing? All living things are related. Some relationships are easy to see—your pet cat may not roar like a lion, but it clearly resembles one. Other relationships are less obvious.

43. Warm Up • 1. In your notebook, construct a table that has 5 columns & 6 rows. In the columns, write the following headings: Animal Group, Example, Legs, Fins, and Tail. Then, place the following animal groups in their own row: Mammal, Bird, Fish, Amphibian, Reptile, and Insect. • 2. Give one example for each group, and then fill in the information for that example. For Legs, write in the number of legs that each animal has. Do animals with fins have legs? Do animals with wings have legs? If so, how many? • 3. Can you tell from your table if a fish is more closely related to a bird or to an amphibian? Explain your answer.

44. Animal Example Legs Fins Tail

45. Animal Example Legs Fins Tail

46. Darwin Presents His Case • It took 25 years for Darwin to present his Theory of Evolution • 1859 – “On the Origin of Species” • This book proposed: 1. a mechanism for Evolution called Natural Selection 2. Evolution has been taking place for millions of years & continues today

47. Details of the Origin of Species • Inherited Variations – differences that are passed from parents to offspring - Darwin had no idea how it happened - We now know it is caused by variations in genes - variations are found in both wild and domesticated living things

48. Artificial Selection • When nature provides the variations and humans select specific variations that they find useful • Produces many diverse domestic animals & plants • Example – breeding only the fastest horses

49. The Struggle for Existence • Darwin was convinced that Artificial Selection worked in nature. • He knew that: ↑ birth rates & ↓ of basic needs = competition of resources Struggle For Existence: Members of each species regularly compete for the necessities of life Ex. Faster, bigger predators catch more prey Faster, camouflaged, & protected prey will not be eaten

50. The Struggle for Existence (cont.) • Key Factor – how well suited an organism to its environment • Fitness – ability of an individual to survive & reproduce in its own environment **the ability to ADAPT = ↑ FITNESS**