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Chapter 15 Principles of Evolution

Chapter 15 Principles of Evolution. Summary of Darwin’s Observations and Conclusions. What is Evolution?. The definition Biological evolution, simply put, is descent with modification. Evolution helps us to understand the history of life.

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Chapter 15 Principles of Evolution

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  1. Chapter 15 Principles of Evolution

  2. Summary of Darwin’s Observations and Conclusions

  3. What is Evolution? • The definitionBiological evolution, simply put, is descent with modification. • Evolution helps us to understand the history of life.

  4. The explanationBiological evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.

  5. The central idea of biological evolution is that all life on Earth shares a common ancestor, just as you and your cousins share a common grandmother.

  6. Through the process of descent with modification, the common ancestor of life on Earth gave rise to the fantastic diversity that we see documented in the fossil record and around us today. Evolution means that we're all distant cousins: humans and oak trees, hummingbirds and whales.

  7. Evidence for evolution comes from geology and the fossil record. These are examples of fossils from different time periods. Each layer of rock represents a different time period in earth’s history.

  8. Darwin’s Finches demonstrate that organisms can change over time. Adaptations best suited for a particular environment become more common in offspring.

  9. Fossil record of the Evolution of the Horse. Notice the leg and tooth morphology

  10. Convergent Evolution leads to Analogous Structures. Organisms in the same environment tend to develop similar structures and look similar even though they are distantly related.

  11. Another example of Convergent Evolution. Notice the body shape and coloring

  12. Divergent Evolution leads to Homologous structures. The swallow and the penguin are both birds, but they live in different environments. The swallow is more closely related to the penguin even though it may look more like the mayfly. Even though the penguin looks more like the seal, it is more closely related to the swallow.

  13. More homologous structures among vertebrates. Notice the basic bone pattern but different functions Darwin’s Theory suggests such similar bone patterns were due to a common ancestor.

  14. Vestigial Structures are evidence of common ancestry. • Vestigial structures in humans include • Wisdom teeth • Appendix • The muscle that wiggles your ears • The gene that codes for the production of Vitamin C

  15. Artificial selectionIf humans can select traits of offspring, Why can’t Nature?

  16. More examples of artificial selection Dogs from wolves Corn from teosinte

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