1. Big Idea #1: Part A –Section #1 Natural Selection as a Mechanism Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Edited by Brian McClain 2012

2. BIG IDEA 1: The Process of Evolution Drives Diversity and Unity of Life. A. Evolution: Change over Time 1. Natural Selection as a mechanism (22.1, 22.2, 23.2) 2. Natural Selection acts on phenotypes (23.1, 23.4) 3. Evolutionary change is random (23.3) 4. Evolution is supported by scientific evidence(22.3)

3. To understand why Darwin’s ideas were revolutionary, we must examine them in relation to other Western ideas about Earth and its life Concept 22.1: The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

4. Fig. 22-2 American RevolutionFrench RevolutionU.S. Civil War 1900 1850 1800 1750 1795 1809 1798 1830 1831–1836 1837 1859 1837 1844 1858 The Origin of Species is published. Wallace sends his hypothesis to Darwin. Darwin begins his notebooks. Darwin writes essay on descent with modification. Darwin travels around the world on HMS Beagle. Malthus publishes “Essay on the Principle of Population.” Lyell publishes Principles of Geology. Lamarck publishes his hypothesis of evolution. Hutton proposes his theory of gradualism. Linnaeus (classification) Cuvier (fossils, extinction) Malthus (population limits) Lamarck (species can change) Hutton (gradual geologic change) Lyell (modern geology) Darwin (evolution, natural selection) Wallace (evolution, natural selection)

5. Scala Naturae and Classification of Species The Greek philosopher Aristotle viewed species as fixed and arranged them on a scala naturae Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

6. Carolus Linnaeus interpreted organismal adaptations as evidence that the Creator had designed each species for a specific purpose Linnaeus was the founder of taxonomy, the branch of biology concerned with classifying organisms Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

7. Ideas About Change over Time The study of fossils helped to lay the groundwork for Darwin’s ideas Fossils are remains or traces of organisms from the past, usually found in sedimentary rock, which appears in layers or strata Video: Grand Canyon Video: Grand Canyon Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

8. Fig. 22-3 Younger stratum with more recent fossils Layers of deposited sediment Older stratum with older fossils

9. Paleontology, the study of fossils, was largely developed by French scientist Georges Cuvier Cuvier advocated catastrophism, speculating that each boundary between strata represents a catastrophe Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

10. Geologist Charles Lyell perceived that changes in Earth’s surface can result from slow continuous actions still operating today Lyell’s principle of uniformitarianism states that the mechanisms of change are constant over time This view strongly influenced Darwin’s thinking Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

11. Lamarck’s Hypothesis of Evolution use and disuseLamarck hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics The mechanisms he proposed are unsupported by evidence Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

12. Fig. 22-4

13. As the 19th century dawned, it was generally believed that species had remained unchanged since their creation However, a few doubts about the permanence of species were beginning to arise Concept 22.2: Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

14. Darwin’s Research As a boy and into adulthood, Charles Darwin had a consuming interest in nature Darwin first studied medicine (unsuccessfully), and then theology at Cambridge University After graduating, he took an unpaid position as naturalist and companion to Captain Robert FitzRoy for a 5-year around the world voyage on the Beagle Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

15. The Voyage of the Beagle During his travels on the Beagle, Darwin collected specimens of South American plants and animals He observed adaptations of plants and animals that inhabited many diverse environments Darwin was influenced by Lyell’s Principles of Geology and thought that the earth was more than 6000 years old Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

16. Fig. 22-5 NORTH AMERICA EUROPE AFRICA AUSTRALIA GREAT BRITAIN SOUTH AMERICA ATLANTIC OCEAN PACIFIC OCEAN Cape of Good Hope Tierra del Fuego Cape Horn Tasmania New Zealand Andes Equator The Galápagos Islands Pinta Marchena Genovesa Santiago Daphne Islands Pinzón Fernandina Isabela San Cristobal Santa Fe Santa Cruz Florenza Española His interest in geographic distribution of species was kindled by a stop at the Galápagos Islands near the equator west of South America

17. Fig. 22-5a Darwin in 1840

18. Fig. 22-5b The Galápagos Islands Pinta Marchena Genovesa Santiago Daphne Islands Pinzón Fernandina Isabela San Cristobal Santa Fe Santa Cruz Florenza Española

19. Video: Galápagos Marine Iguana Video: Galápagos Marine Iguana Video: Galápagos Tortoises Video: Galápagos Tortoises Video: Galápagos Sea Lion Video: Galápagos Sea Lion Video: Galápagos Islands Overview Video: Galápagos Islands Overview Video: Blue-footed Boobies Courtship Ritual Video: Blue-footed Boobies Courtship Ritual Video: Albatross Courtship Ritual Video: Albatross Courtship Ritual Video: Soaring Hawk Video: Soaring Hawk Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

20. Darwin’s Focus on Adaptation In reassessing his observations, Darwin perceived adaptation to the environment and the origin of new species as closely related processes From studies made years after Darwin’s voyage, biologists have concluded that this is indeed what happened to the Galápagos finches Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

21. Fig. 22-6 (a) Cactus-eater(c) Seed-eater (b) Insect-eater

22. Fig. 22-6a (a) Cactus-eater

23. Fig. 22-6b (b) Insect-eater

24. Fig. 22-6c (c) Seed-eater

25. In 1844, Darwin wrote an essay on the origin of species and natural selection but did not introduce his theory publicly, anticipating an uproar In June 1858, Darwin received a manuscript from Alfred Russell Wallace, who had developed a theory of natural selection similar to Darwin’s Darwin quickly finished The Origin of Species and published it the next year Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

26. The Origin of Species Darwin developed two main ideas: – Descent with modification explains life’s unity and diversity – Natural selection is a cause of adaptive evolution Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

27. Descent with Modification Darwin never used the word evolution in the first edition of The Origin of Species “descent with modification”The phrase “descent with modification” summarized Darwin’s perception of the unity of life The phrase refers to the view that all organisms are related through descent from an ancestor that lived in the remote past Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

28. In the Darwinian view, the history of life is like a tree with branches representing life’s diversity Darwin’s theory meshed well with the hierarchy of Linnaeus Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

29. Fig. 22-8 Hyracoidea (Hyraxes) Sirenia (Manatees and relatives) Moeritherium Barytherium Deinotherium Mammut Elephas maximus (Asia) Stegodon Mammuthus Loxodonta africana (Africa) Loxodonta cyclotis (Africa) 0 10 4 2 5.5 24 34 Millions of years ago Years ago Platybelodon

30. Fig. 22-8a Elephas maximus (Asia) Stegodon Mammuthus Loxodonta africana (Africa) Loxodonta cyclotis (Africa) 0 10 4 25.524 34 Millions of years ago Years ago Platybelodon

31. Artificial Selection, Natural Selection, and Adaptation Darwin noted that humans have modified other species by selecting and breeding individuals with desired traits, a process called artificial selection Darwin then described four observations of nature and from these drew two inferences Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

32. Fig. 22-9 Kale Kohlrabi Brussels sprouts Leaves Stem Wild mustard Flowers and stems Broccoli Cauliflower Flower clusters Cabbage Terminal bud Lateral buds

33. Observation #1: Members of a population often vary greatly in their traits Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

34. Observation #2: Traits are inherited from parents to offspring Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

35. Observation #3: All species are capable of producing more offspring than the environment can support Observation #4: Owing to lack of food or other resources, many of these offspring do not survive

36. Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

37. Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

38. Thomas MalthusDarwin was influenced by Thomas Malthus who noted the potential for human population to increase faster than food supplies and other resources If some heritable traits are advantageous, these will accumulate in the population, and this will increase the frequency of individuals with adaptations This process explains the match between organisms and their environment Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

39. Natural Selection: A Summary Individuals with certain heritable characteristics survive and reproduce at a higher rate than other individuals Natural selection increases the adaptation of organisms to their environment over time If an environment changes over time, natural selection may result in adaptation to these new conditions and may give rise to new species Video: Seahorse Camouflage Video: Seahorse Camouflage Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

40. Fig. 22-12 (b) A stick mantid in Africa (a) A flower mantid in Malaysia

41. Fig. 22-12a (a) A flower mantid in Malaysia

42. Fig. 22-12b (b) A stick mantid in Africa

43. Note that individuals do not evolve; populations evolve over time Natural selection can only increase or decrease heritable traits in a population Adaptations vary with different environments Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings