Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings. BIOLOGY A GUIDE TO THE NATURAL WORLD FOURTH EDITION DAVID KROGH An Introduction to Evolution: Charles Darwin, Evolutionary Thought, and the Evidence of Evolution

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Evolution and Its Core Principles

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Common Descent with Modification Within the theory of evolution, a key principle is that of common descent with modification. This principle describes the process by which species of living things can undergo modification over time, with such change sometimes resulting in the formation of new, separate species.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Common Descent with Modification All species on Earth have descended from other species, and a single, common ancestor lies at the base of the evolutionary tree.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Natural Selection A second key principle in the theory of evolution concerns natural selection. Natural selection is a process in which the differential adaptation of individual organisms to their environment selects those traits that will be passed on with greater frequency from one generation to the next.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Importance of Evolution as a Concept The theory of evolution has an importance beyond the domain of biology. Through it, human beings have become aware that: 1.They are descended from other varieties of living things. 2.The organisms that populate the living world are not fixed entities, but instead are constantly undergoing modification.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Charles Darwin and the Theory of Evolution

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Darwin and the Theory of Evolution Figure 16.1

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Darwin and the Theory of Evolution Charles Darwin deserves primary credit for the theory of evolution. Darwin developed existing ideas about descent with modification while providing a large body of evidence in support of them. He was the first to perceive natural selection as the primary process that drives evolution.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Darwin and the Theory of Evolution Darwin’s insights were inspired by the research he carried out during a five-year voyage he took around the world on the ship HMS Beagle, beginning in 1831.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Darwin and the Theory of Evolution Figure 16.2

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Darwin and the Theory of Evolution Figure 16.3 North America South America Asia Africa Australia equator Europe Dec Oct July 1834 Sept Galapagos Islands Falkland Islands March 1833 March 1834 April 1832 Jan. 1836

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Evolutionary Thinking before Darwin

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Evolutionary Thinking Before Darwin Some of Darwin’s ideas can be traced to the work of Charles Lyell, who noted the dynamic geological nature of the Earth.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Evolutionary Thinking Before Darwin Also important were Jean-Baptiste de Lamark and Georges Cuvier. Lamark noted the possibility of descent with modification. Cuvier noted the extinction of some species on Earth and the appearance of others within different time-frames.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Evolutionary Thinking Before Darwin Figure 16.5

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Darwin’s Insights Following the Beagle’s Voyage

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Darwin’s Insights Darwin understood descent with modification for several years before he comprehended that natural selection was the most important process driving it. It was his reading of a work by Malthus on limits to population growth that sparked his realization about natural selection.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Alfred Russel Wallace

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Alfred Russell Wallace English naturalist Alfred Russel Wallace is the co-discoverer of natural selection as the principal process underlying evolution.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Descent with Modification Is Accepted

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Descent with Modification is Accepted Descent with modification was accepted by most scientists not long after publication of Darwin’s On the Origin of Species by Means of Natural Selection in Scientists accepted it because it explained so many facets of the living world.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Descent with Modification is Accepted Figure 16.8

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Descent with Modification is Accepted Figure 16.7

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Descent with Modification is Accepted Figure 16.9 Pharyngeal slits exist in these five vertebrate animals... sea lampreypond turtlechickendomestic cathuman being pharyngeal slits... evidence that all five evolved from a common ancestor

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Darwin Doubted: The Controversy over Natural Selection

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Controversy over Natural Selection The hypothesis that natural selection is the most important process underlying evolution was not generally accepted until the middle of the twentieth century.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Controversy over Natural Selection Its acceptance hinged on a modern synthesis in the theory of evolution that brought together lines of evidence from genetics, the fossil record, and the distribution of organisms throughout the world.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Opposition to the Theory of Evolution

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Opposition to the Theory of Evolution Even today, the theory of evolution is regularly challenged as being unproven or simply wrong.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Opposition to the Theory of Evolution One factor leading to the appearance of a “scientific debate” over evolution is confusion about the meaning of the word theory. Though the average person may equate “theory” with speculation, in science a theory is a general set of principles supported by a lot of evidence that explains some aspect of the natural world.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Evidence for Evolution

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. The Evidence for Evolution Six lines of evidence are consistent with the theory of evolution.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 1. Radiometric Dating First, radiometric dating has confirmed the immense age of the Earth—an age that is consistent with the long periods of time scientists believe it has taken species to evolve.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 2. Fossils Second, around the globe, fossils from the same evolutionary periods are consistently found together in geologic strata.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 2. Fossils Moreover, there is excellent agreement between the relative ages assigned to fossils by evolutionary theory and the absolute ages assigned to them by radiometric dating.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 2. Fossils Figure 16.10

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 3. Comparative Morphology and Embryology Third, the theory of evolution explains the common occurrence of homologous physical structures in different organisms.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 3. Comparative Morphology and Embryology Figure gorillacatwhalebat

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 4. Evidence from Biogeography Fourth, island biogeography—the geographic distribution of species on Earth’s islands—is explained by the theory of evolution.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 4. Evidence from Biogeography Figure 16.13

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 5. Evidence from Gene Modification Fifth, variations found in the DNA sequences of various organisms are consistent with evolutionary theory.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 5. Evidence from Gene Modification Figure Large number of base differences between humans and yeast Small number of base differences between humans and pigs Number of DNA nucleotide base differences in the cytochrome c oxidase gene human pig duck snake tunamothyeast

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. 6. Experimental Evidence And sixth, experimental demonstrations of evolution have been carried out in the laboratory and in nature.

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings. Principles of Evolution PLAY Animation 16.1: Principles of Evolution