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Transcript
Chapter 13 How Populations Evolve PowerPoint® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Lectures by Chris C. Romero, updated by Edward J. Zalisko © 2010 Pearson Education, Inc. Remember This © 2010 Pearson Education, Inc. CHARLES DARWIN AND THE ORIGIN OF SPECIES • Charles Darwin published On the Origin of Species by Means of Natural Selection, November 24, 1859. • Darwin presented two main concepts: – Life evolves – Change occurs as a result of “descent with modification,” with natural selection as the mechanism Natural selection is a process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are individuals with other characteristics. © 2010 Pearson Education, Inc. © 2010 Pearson Education, Inc. • Natural selection leads to: – A population (a group of individuals of the same species living in the same place at the same time) changing over generations – Evolutionary adaptation • In one modern definition of evolution, the genetic composition of a population changes over time. © 2010 Pearson Education, Inc. Darwin’s Cultural and Scientific Context • The Origin of Species challenged the notion that the Earth was: – Relatively young – Populated by unrelated species © 2010 Pearson Education, Inc. The Idea of Fixed Species • The Greek philosopher Aristotle held the belief that species are fixed and do not evolve. • The Judeo-Christian culture fortified this idea with a literal interpretation of the Bible and suggested the Earth may only be 6,000 years old. © 2010 Pearson Education, Inc. Lamarck and Evolutionary Adaptations • In the mid-1700s, the study of fossils began to take form as a branch of science. • Naturalist Georges Buffon noted that: – The Earth may be more than 6,000 years old – There are similarities between fossils and living species – Fossil forms might be ancient versions of similar living species © 2010 Pearson Education, Inc. • Jean Baptiste Lamarck suggested that organisms evolved by the process of adaptation by the inheritance of acquired characteristics, now known to be incorrect. 1--Use and disuse & 2--Inheritance of acquired traits © 2010 Pearson Education, Inc. © 2010 Pearson Education, Inc. 1837 Darwin begins analyzing his specimens and writing his notebooks on the origin of species. 1844 Darwin writes his essay 1865 on the origin of species. Mendel publishes papers on genetics. 1870 1800 1809 Lamarck publishes 1830 his theory Lyell publishes of evolution. Principles of Geology. 1809 Charles Darwin is born. 1831–36 Darwin travels around the world on the HMS Beagle. 1858 Wallace sends an account of his theory to Darwin. 1859 Darwin publishes The Origin of Species. Green sea turtle in the Galápagos Islands Figure 13.2 Darwin in 1840 Great Britain Europe Asia North America ATLANTIC OCEAN HMS Beagle Africa Galápagos Islands PACIFIC OCEAN Pinta Marchena Equator Genovesa South America Equator Santiago Daphne Islands 0 40 km Santa Santa Cruz Fe Florenza San Cristobal PACIFIC OCEAN Cape of Good Hope Andes Isabela 0 Australia Pinzón Fernandina Española Cape Horn 40 miles Tierra del Fuego Tasmania New Zealand Figure 13.3 • Darwin was intrigued by: – The geographic distribution of organisms on the Galápagos Islands – Similarities between organisms in the Galápagos and those in South America © 2010 Pearson Education, Inc. Figure 13.4 © 2010 Pearson Education, Inc. • Darwin was strongly influenced by the writings of geologist Charles Lyell. • Lyell suggested that the Earth: – Is very old – Was sculpted by gradual geological processes that continue today • Darwin applied Lyell’s principle of gradualism to the evolution of life on Earth. © 2010 Pearson Education, Inc. Descent with Modification • Darwin made two main points in The Origin of Species: – Organisms inhabiting Earth today descended from ancestral species – Natural selection was the mechanism for descent with modification © 2010 Pearson Education, Inc. EVIDENCE OF EVOLUTION • Biological evolution leaves observable signs. • We will examine five of the many lines of evidence in support of evolution: – The fossil record – Biogeography – Comparative anatomy – Comparative embryology – Molecular biology © 2010 Pearson Education, Inc. The Fossil Record • Fossils are: – Imprints or remains of organisms that lived in the past – Often found in sedimentary rocks © 2010 Pearson Education, Inc. • The fossil record: – Is the ordered sequence of fossils as they appear in rock layers – Reveals the appearance of organisms in a historical sequence – Fits the molecular and cellular evidence that prokaryotes are the ancestors of all life © 2010 Pearson Education, Inc. Figure 13.5 Biogeography • Biogeography is the study of the geographic distribution of species that first suggested to Darwin that today’s organisms evolved from ancestral forms. © 2010 Pearson Education, Inc. © 2010 Pearson Education, Inc. © 2010 Pearson Education, Inc. Comparative Anatomy • Comparative anatomy – Is the comparison of body structure between different species – Confirms that evolution is a remodeling process © 2010 Pearson Education, Inc. • Homology is: – The similarity in structures due to common ancestry – Illustrated by the remodeling of the pattern of bones forming the forelimbs of mammals © 2010 Pearson Education, Inc. Figure 13.6-2 Human Cat Whale Bat Figure 13.8 Whale Evolution Whales are thought to have evolved from 4legged mammals © 2010 Pearson Education, Inc. Pelvic bones in whales are homologous to cows • Vestigial structures: – Are remnants of features that served important functions in an organism’s ancestors – Now have only marginal, if any, importance © 2010 Pearson Education, Inc. Comparative Embryology • Early stages of development in different animal species reveal additional homologous relationships. – For example, pharyngeal pouches appear on the side of the embryo’s throat, which: – Develop into gill structures in fish – Form parts of the ear and throat in humans – Comparative embryology of vertebrates supports evolutionary theory. © 2010 Pearson Education, Inc. Pharyngeal pouches Post-anal tail Chicken embryo Human embryo Figure 13.9 © 2010 Pearson Education, Inc. Molecular Biology • The hereditary background of an organism is documented in: – Its DNA – The proteins encoded by the DNA • Evolutionary relationships among species can be determined by comparing: – Genes – Proteins of different organisms © 2010 Pearson Education, Inc. Primate Percent of selected DNA sequences that match a chimpanzee’s DNA 92% 96% 100% Chimpanzee Human Gorilla Orangutan Gibbon Old World monkey Figure 13.10 NATURAL SELECTION • Darwin noted the close relationship between adaptation to the environment and the origin of new species. • The evolution of finches on the Galápagos Islands is an excellent example. © 2010 Pearson Education, Inc. Darwin’s Theory of Natural Selection • Darwin based his theory of natural selection on two key observations: – All species tend to produce excessive numbers of offspring – Organisms vary, and much of this variation is heritable © 2010 Pearson Education, Inc. • Observation 1: Overproduction – All species tend to produce excessive numbers. – This leads to a struggle for existence. This = Competition © 2010 Pearson Education, Inc. • Observation 2: Individual variation – Variation exists among individuals in a population. – Much of this variation is heritable. All Offspring are Different so….. Some Survive and Some Don’t or “Natural Selection” © 2010 Pearson Education, Inc. Natural Selection in Action • Examples of natural selection include: – Pesticide-resistant insects – Antibiotic-resistant bacteria – Drug-resistant strains of HIV © 2010 Pearson Education, Inc. Insecticide application Chromosome with gene conferring resistance to pesticide Figure 13.14-1 Insecticide application Chromosome with gene conferring resistance to pesticide Survivors Reproduction Figure 13.14-3 Sources of Genetic Variation • Genetic variation results from: – Mutations, changes in the DNA of an organism – Sexual recombination, the shuffling of alleles during meiosis © 2010 Pearson Education, Inc.