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Ch6 Sec1

Ch6 Sec1. Darwin’s Theory. Key Concepts. What important observations did Darwin make on his voyage? What hypothesis did Darwin make to explain the differences between similar species? How does natural selection lead to evolution?. Key Terms. Species Fossil Adaptations Evolution

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Ch6 Sec1

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  1. Ch6 Sec1 Darwin’s Theory

  2. Key Concepts • What important observations did Darwin make on his voyage? • What hypothesis did Darwin make to explain the differences between similar species? • How does natural selection lead to evolution?

  3. Key Terms • Species • Fossil • Adaptations • Evolution • Scientific theory • Natural selection • Variation

  4. Ch6 Sec1 • Darwin’s Observations • Darwin’s important observations included the diversity of living things, the remains of ancient organisms, and the characteristics of organisms on the Galapagos Islands • Diversity • Species is a group of similar organisms that can mate with each other and produce fertile offspring • Fossil is the preserved remains or traces of an organism that lived in the past

  5. Ch6 Sec1 • Galapagos Organisms • Comparisons to South American Organisms • Comparisons Among the Islands • Adaptations, a trait that helps an organism survive and reproduce

  6. Ch6 Sec1 • Evolution • Darwin’s Reasoning • Darwin reasoned that plants or animals that arrived on the Galapagos Islands faced conditions that were different from those on the mainland. Perhaps, Darwin hypothesized, the species gradually changed over many generations and became better adapted to the new conditions • Evolution is the gradual change in a species over time • Scientific theory is a well-tested concept that explains a wide range of observations • Selective Breeding

  7. Ch6 Sec1 • Natural Selection is the process by which individuals that are better adapted to their environment are more likely to survive and reproduce then other members of the same species • Overproduction • Variation is any difference between individuals of the same species • Selection • Darwin proposed that , over a long time, natural selection can lead to change. Helpful variations may gradually accumulate in a species, while unfavorable ones may disappear • Environmental Change • Genes and Natural Selection

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