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Tree of Life What mechanism gave rise to the diversity of life that we see today? Theory of Evolution by means of Natural Selection Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Charles Darwin 1809- 1882 • While on the voyage of the HMS Beagle in the 1830s as ship’s naturalist to Captain Fitzroy- Mapping Expedition • Charles Darwin observed similarities between living and fossil organisms and the diversity of life on the Galápagos Islands North America Great Britain Europe Asia ATLANTIC OCEAN PACIFIC OCEAN Africa PACIFIC OCEAN Equator The Galápagos Islands PACIFIC OCEAN Pinta South America Genovesa Australia Equator Santiago Pinzón Fernandina 0 0 Cape of Good Hope Tasmania Isabela Figure 13.1B Daphne Islands Andes Marchena Santa Santa Cruz Fe Cape Horn San Cristobal 40 km Florenza 40 miles Española Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Tierra del Fuego New Zealand DARWIN’S THEORY OF EVOLUTION Voyage of the Beagle helped Darwin frame his theory of evolution On his visit to the Galápagos Islands: Charles Darwin observed many unique organisms- marine iguanas, tortoises, and the finches. Each of the above was similar to a organism found on the mainland and each sub group on the different islands seemed similar to each other. Figure 13.1A Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 13.2 Darwin proposed natural selection as the mechanism of evolution 1.Produce more offspring than the environment can support 2. Individuals vary in many characteristics that can be inherited Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings • Darwin reasoned that natural selection – Results in favored certain traits being represented more and more in subsequent generations and unfavored ones less and less. Differential selection or differential reproduction Survival of the fittest Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Only the those with the best combinations of traits survive to reproduce and pass their genes on- Clown, Fool, or Simply Well Adapted? • The blue-footed booby – Is a type of bird living in the Galápagos Islands Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings • This type of bird possesses many specialized characteristics, called evolutionary adaptations – Which are inherited traits that enhance its ability to survive and reproduce in its particular environment Birds need to balance the adaptations of living on land and being successful aquatic predators Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings • Darwin found convincing evidence for his ideas in the results of artificial selection – The selective breeding of domesticated plants and animals Hundreds to thousands of years of breeding (artificial selection) Ancestral dog (wolf) Figure 13.2A Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Figure 13.2B • Darwin proposed that living species – Are descended from earlier life forms and that natural selection is the mechanism of evolution African wild dog Coyote Wolf Thousands to millions of years of natural selection Figure 13.2C Ancestral canine Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Fox Jackal