Copyright © 2005 Pearson Prentice Hall, Inc. 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)

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eggs in nest fossilized feces (coprolites) bones footprints skin impression

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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)

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Large ground finch, beak suited to large seeds Small ground finch, beak suited to small seeds Warbler finch, beak suited to insects Vegetarian tree finch, beak suited to leaves

Copyright © 2005 Pearson Prentice Hall, Inc. Relatively constant resources and population size over time Potential for rapid reproduction Competition for survival and reproduction Variability in structures and behaviors NATURAL SELECTION: On the average, the fittest organisms leave the most offspring Some variability is inherited EVOLUTION: The genetic makeup of the population changes over time, driven by natural selection Observation Conclusion based on observation How Does Natural Selection Work? A flowchart of evolutionary reasoning (F14.5 p. 272)

Copyright © 2005 Pearson Prentice Hall, Inc How Does Natural Selection Work? Modern Genetics Confirmed Darwin’s Assumption of Inheritance Natural Selection Modifies Populations Over Time –Figure 14.6 The evolution of the horse (p. 272)

Copyright © 2005 Pearson Prentice Hall, Inc Merychippus Hyracotherium Mesohippus Hipparion AnchitheriumArchaeohippus Pliohippus Equus Paleotheres grazing millions of years ago tooth forefoot browsing

Copyright © 2005 Pearson Prentice Hall, Inc. 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. Pterodactyl Bird Bat Dolphin Seal Dog SheepShrew humerus ulna metacarpals phalanges radius carpals Human GRASPING RUNNING SWIMMING FLYING

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

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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

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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