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Chapter 14 Principles of Evolution • How Did Evolutionary Thought Evolve? • Early Biological Thought Did Not Include the Concept of Evolution • Exploration of New Lands: Staggering Diversity of Life • Fossil Discoveries: Life Had Changed Over Time – The Grand Canyon of the Colorado River F14.1 – Types of fossils (F14.2 p. 266) – Fossils of extinct organisms (F14.3 p. 267) Copyright © 2005 Pearson Prentice Hall, Inc. Copyright © 2005 Pearson Prentice Hall, Inc. eggs in nest fossilized feces (coprolites) Copyright © 2005 Pearson Prentice Hall, Inc. bones footprints skin impression Copyright © 2005 Pearson Prentice Hall, Inc. How Did Evolutionary Thought Evolve? • Some Scientists Devised Nonevolutionary Explanations for Fossils • A Few Scientists Speculated That Life Had Evolved • Geology Provided Evidence That: – Earth Is Exceedingly Old – Gradual Change Over a Long Time Produces Large Differences • Some Pre-Darwin Biologists Proposed Mechanisms for Evolution • Darwin and Wallace Proposed a Mechanism of Evolution – Darwin’s finches, residents of the Galapagos Islands (F14.4 p. 269) Copyright © 2005 Pearson Prentice Hall, Inc. Copyright © 2005 Pearson Prentice Hall, Inc. Copyright © 2005 Pearson Prentice Hall, Inc. Large ground finch, beak suited to large seeds Warbler finch, beak suited to insects Copyright © 2005 Pearson Prentice Hall, Inc. Small ground finch, beak suited to small seeds Vegetarian tree finch, beak suited to leaves How Does Natural Selection Work? •A flowchart of evolutionary reasoning (F14.5 p. 272) Potential for rapid reproduction Relatively constant resources and population size over time Competition for survival and reproduction Variability in structures and behaviors NATURAL SELECTION: On the average, the fittest organisms leave the most offspring Observation Conclusion based on observation Copyright © 2005 Pearson Prentice Hall, Inc. Some variability is inherited EVOLUTION: The genetic makeup of the population changes over time, driven by natural selection 14.2 How Does Natural Selection Work? • 14.2.1 Modern Genetics Confirmed Darwin’s Assumption of Inheritance • 14.2.2 Natural Selection Modifies Populations Over Time – Figure 14.6 The evolution of the horse (p. 272) Copyright © 2005 Pearson Prentice Hall, Inc. Pliohippus 5 Hipparion Archaeohippus Anchitherium Merychippus Mesohippus forefoot tooth 25 35 Hyracotherium Paleotheres 50 Copyright © 2005 Pearson Prentice Hall, Inc. browsing millions of years ago 1 grazing Equus 0 How Do We Know That Evolution Has Occurred? • Fossils Provide Evidence of Evolutionary Change Over Time • Comparative Anatomy Gives Evidence of Descent with Modification – Homologous Structures Provide Evidence of Common Ancestry (F14.7 p. 274) – Functionless, Vestigial Structures Inherited from Ancestors (F14.8 p. 275) Copyright © 2005 Pearson Prentice Hall, Inc. humerus Pterodactyl Dolphin Dog ulna radius carpals metacarpals phalanges Human Bird Bat FLYING Seal Sheep Shrew SWIMMING RUNNING GRASPING Copyright © 2005 Pearson Prentice Hall, Inc. Salamander Baleen whale Boa constrictor Copyright © 2005 Pearson Prentice Hall, Inc. How Do We Know That Evolution Has Occurred? • Some Anatomical Similarities from Evolution in Similar Environments • Analogous structures (F14.9 p. 276) • Similar Embryonic Stages Suggest Common Ancestry (F14.10 p. 276) • Biochemical and Genetic Analyses Reveal Relatedness Among Diverse Organisms Copyright © 2005 Pearson Prentice Hall, Inc. Copyright © 2005 Pearson Prentice Hall, Inc. Copyright © 2005 Pearson Prentice Hall, Inc. What Is the Evidence That Populations Evolve by Natural Selection? • Artificial Selection Controlled Breeding Modifies Organisms (F14.11 p. 277) • Evolution by Natural Selection Occurs Today – When Fewer Predators Are Present, Brighter Coloration Can Evolve – Natural Selection Can Lead to Pesticide Resistance – Experiments Can Demonstrate Natural Selection – Selection Acts on Random Variation to Favor the Traits That Work Best in Particular Environments Copyright © 2005 Pearson Prentice Hall, Inc. Copyright © 2005 Pearson Prentice Hall, Inc. What Is the Evidence That Populations Evolve by Natural Selection? • Evolution by Natural Selection Occurs Today – When Fewer Predators Are Present, Brighter Coloration Can Evolve – Natural Selection Can Lead to Pesticide Resistance Activity 14.2 – Experiments Can Demonstrate Natural Selection – Selection Acts on Random Variation to Favor the Traits That Work Best in Particular Environments Copyright © 2005 Pearson Prentice Hall, Inc.