Chapter 22 Descent with Modification

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

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Chapter 22: Descent with Modification: A Darwinian View of Life 22.1: The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging species Scala Naturae and Classification of Species - Several Greek philosophers believed that life might change over time, but Aristotle viewed species as fixed o He arranged them on a scale, later called the scala naturae , based on their complexity o He believed that creatures had been designed by God and therefore were well-adapted to their environments - Carolus Linnaeus was a Swedish physician and botanist who wanted to classify nature o He developed the binomial naming system that is still used today His classification system was nested He did not attribute the resemblance among species to evolutionary trends, but rather to the pattern of their creation Ideas about change over time - Many of Darwin’s ideas came from others’ work on fossils, mainly the idea that older layers of sediment are underneath newer layers, called strata o Paleontology: study of fossils developed by Georges Cuvier - Georges Cuvier observed that the older the stratum, the more different they were from current life forms o Also, from one layer to the next, some fossils disappeared and others appeared He concluded that extinction events were common, and that other organisms from surrounding areas would come to fill the niches o He advocated catastrophism The idea that events in the past occurred suddenly and were caused by mechanisms different from those operating in the present - Other scientists believed that change happened gradually over time o James Hutton believed that Earth’s geologic features could be explained by gradual mechanisms that were still operating Charles Lyell used this as inspiration for his idea of uniformitarianism The idea that mechanisms of change are constant over time Lamarck’s Hypothesis of Evolution - By the 18 th century, several naturalists had argued that life evolves as environments change - Lamarck was the first to propose a m ech anism for how life chang es over time, even though wrong o Use and disuse: p arts of the body that are us ed extensively beco m e larger a nd strong er, not us ed d et eriorate o Inheritance of acquired characteristics: a n organism could p ass on thes e modifications t o He also thought that evolution happ ens b ecaus e organism h ave a n innate drive to beco m co mplex 22.2: Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life Darwin’s research - Although he was sent to m e dical school, he wanted to be a naturalist; h e quit and intended clergym an after gradu ation from Cambridge University The Voyage of the Beagle - The ship was suppos ed to m a p poorly known are as of South America
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This note was uploaded on 04/21/2009 for the course BISC 120Lg taught by Professor 11:00-01:50pm during the Fall '06 term at USC.

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

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