Chapter%2022%20Outline - Chapter22:: TheOriginofSpecies

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Chapter 22: Descent With Modification: A Darwinian View of Life Endless Forms Most Beautiful A new era of biology began in 1859 when Charles Darwin published  The Origin of Species  The Origin of Species  focused biologists’ attention on the great diversity of organisms Darwin noted that current species are descendants of ancestral species Evolution  can be defined by Darwin’s phrase  descent with modification Evolution can be viewed as both a pattern and a process Figure 22.1 The Darwinian revolution Challenged traditional views of a young Earth inhabited by unchanging species  Ideas About Change over Time The study of  fossils  helped to lay the groundwork for Darwin’s ideas Fossils are remains or traces of organisms from the past, usually found in sedimentary rock,  which appears in layers or  strata Figure 22.3 Georges Cuvier Developed the study of fossils,  Paleontology   Advocated  catastrophism   each boundary between strata represents a catastrophe James Hutton and Charles Lyell Changes in Earth’s surface can result from slow continuous actions  still operating today Lyell’s principle of  uniformitarianism  states that the mechanisms of change are constant over  time This view strongly influenced Darwin’s thinking Lamarck’s Hypothesis of Evolution Species evolve through use and disuse of body parts and the inheritance of acquired  characteristics The mechanisms he proposed are unsupported by evidence Descent with modification by natural selection As the 19th century dawned, it was generally believed that  species had remained unchanged since their creation However, a few doubts about the permanence of species were beginning to arise The Voyage of the Beagle
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During his travels on the  Beagle,  Darwin collected specimens of South American plants and  animals He observed adaptations of plants and animals that inhabited many diverse environments Darwin was influenced by Lyell’s  Principles of Geology 
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Chapter%2022%20Outline - Chapter22:: TheOriginofSpecies

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