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Unformatted text preview: Chapter 22 Biology 1202 Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life. (22.2) As the nineteenth century dawned, it was generally believed that species had remained unchanged since their creation. How did Charles Darwin become the lightning rod for a revolutionary view of life? • Darwin’s Research Charles Darwin was born in 1809 in Shrewsburg, England. He was originally enrolled in medical school, but then went to college to become a clergyman. Then Darwin became a surveyor on the HMS Beagle. o The Voyage of the Beagle The primary mission of the Beagle was to go along the South American coastline. Darwin spent most of his time on the shore observing and collecting South American plants and animals and compared them to the characteristics of other animals from the different regions of South America. The plants and animals in temperate regions of South America more closely resembled species from the South American tropics, not temperate Europe, and the fossils he found were very different from any of the living species but still resembled the South American organisms. While in the Andes, Darwin inferred that the fossils he saw were raised there by earthquakes, supporting the idea that the Earth was more than a few thousand years old. This was an idea he read about in Lyell’s Principles of Geology. Other than Lyell, everyone else at the time thought that the Earth was very “young”. 1 | P a g e Chapter 22 Biology 1202 The Beagle stopped at the Galapagos Islands, where the creatures fascinated Darwin. • Some of the species were similar to the South American species from the mainland but very different from anywhere else in the world. He hypothesized that the Galapagos was colonized by animals from South America that diversified. o Darwin’s Focus on Adaptation Adaptations – Characteristics of organisms that enhance their survival and reproduction in specific environments Adaptation to the environment and the origin of new species are closely related processes. Studies made after Darwin’s voyage concluded that a new species could arise from an ancestral form by the gradual accumulation of adaptations to a different environment. Animals, such as finches, adapted to the types of food that were in their new surroundings by their beaks and behaviors....
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This note was uploaded on 08/29/2010 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.
- Spring '08