Chapter 22 - Chapter 22 Descent with Modification: A...

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Page Page 1 of 27 of 27 Chapter 22 Chapter 22 Descent with Modification: A Darwinian View of Life
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Page Page 2 of 27 of 27 Overview: Darwin Introduces a Overview: Darwin Introduces a Revolutionary Theory Revolutionary Theory The Origin of Species Focused biologists’ attention on the great diversity of organisms Darwin’s two major points in his book: Many species of organisms presently inhabiting the Earth are descendants of ancestral species Natural Selection is the mechanism for the evolutionary process Figure 22.1
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Page Page 3 of 27 of 27 The Classification of Species The Classification of Species The Greek philosopher Aristotle (384-322 B.C.) Viewed species as fixed and unchanging A scala naturae existed Carolus Linnaeus (1707 – 1778) Founder of Taxonomy Grouped similar species together and nested these groups within higher, more general categories He argued that adaptations are evidence of Creation
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Page Page 4 of 27 of 27 Fossils, Cuvier, and Catastrophism Fossils, Cuvier, and Catastrophism Georges Cuvier (1769-1832) is considered the founder of Paleontology He noted that deeper rock layers contained fossils increasingly different from current species Each newer (younger) stratum contained some new species and was missing some of the previous stratum’s species He thought that boundaries between rock layers represented major catastrophes, such as floods or droughts Opposed the idea of gradual evolutionary change and advocated Catastrophism
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Page Page 5 of 27 of 27 Gradualism Gradualism Other scientists thought that large changes can take place through the cumulative effect of many small changes over a large period of time Geologists Hutton (1726-1797) and Lyell (1797- 1875) combined ideas led to the theory of Uniformitarianism Slow continuous actions produce changes in Earth’s surface and have been doing so, at the same rate, for a long time.
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Page Page 6 of 27 of 27 Lamarck’s Theory of Evolution Lamarck’s Theory of Evolution Lamarck (1744-1829) was the first to hypothesized HOW species evolve Use and disuse Ex) Giraffe stretching its neck Inheritance of acquired traits Unsupported by current evidence Figure 22.4
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Page Page 7 of 27 of 27 The Origin of Species The Origin of Species HMS Beagle travels the world (1831-1836) Darwin (1809-1882) observes and collects many samples of plants and animals He observed various adaptations of plants and animals in many diverse environments Galápagos Islands of major interest He thought that adaptation to the environment and the origin of new species are closely related processes Darwin developed two main, overarching ideas Descent with Modification (adaptive evolution) explains life’s unity and diversity Natural selection as the cause of evolution
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Page Page 8 of 27 of 27 Galápagos Finches:
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Chapter 22 - Chapter 22 Descent with Modification: A...

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