Chapter 15 Notes


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Chapter 15 Notes

  1. 1. Chapter 15 Notes
  2. 3. Key Terms <ul><li>Evolution : Changes in a population over time. </li></ul><ul><li>Natural Selection : The environment favors individuals to survive and reproduce successfully “AKA, Survival of the Fittest” </li></ul><ul><li>Individuals do not evolve, populations do . </li></ul>
  3. 4. Darwin’s Theory: The Short Version <ul><li>1. Organisms differ; variation is inherited </li></ul><ul><li>2. Organisms produce more offspring than survive </li></ul><ul><li>3. Organisms compete for resources </li></ul><ul><li>4. Organisms with advantages survive to pass those advantages to their children </li></ul><ul><li>5. Species alive today are descended with modifications from common ancestors </li></ul>
  4. 5. Example: Colored Moths <ul><li>The traits that help an organism survive in a particular environment are “selected” in natural selection </li></ul>
  5. 9. Key Terms <ul><li>Adaptation : An inherited characteristic that increases an organism’s ability to survive and reproduce in its specific environment. </li></ul><ul><li>Fitness : The ability to survive and reproduce in a specific environment. Adaptations make an organism more fit. </li></ul>
  6. 10. Key Terms <ul><li>Artificial Selection : Nature provides the variation and human select those variances they find useful. </li></ul><ul><ul><ul><li>Example: a farmer breeds only his best livestock. </li></ul></ul></ul>
  7. 11. Evidence for Evolution <ul><ul><ul><li>1. The Fossil Record </li></ul></ul></ul><ul><ul><ul><li>2. Homologous Body Structures </li></ul></ul></ul><ul><ul><ul><li>3. Similarities in Embroyology </li></ul></ul></ul><ul><ul><ul><li>4. Vestigial Structures </li></ul></ul></ul><ul><ul><ul><li>5. Similarities in DNA and RNA </li></ul></ul></ul>
  8. 12. Homologous Structures <ul><li>Same structures-Different function </li></ul><ul><li>Example: Human arm, bird wing </li></ul>
  9. 13. Homologous Structures
  10. 14. Embryology
  11. 15. Analogous Structures <ul><li>Different structure, Same function </li></ul><ul><li>Example: Butterfly wing, bird wing </li></ul>
  12. 16. Vestigial Structures <ul><li>Body structures that no longer have a use </li></ul><ul><li>Example: Human appendix </li></ul>
  13. 17. Gene Pool <ul><li>Gene Pool : The combined collection of alleles for all traits in a population. </li></ul>
  14. 18. Three Forms of Natural Selection
  15. 19. Sexual Selection <ul><li>Sexual Selection : A special case of selection that occurs when the choice of mates is based on a trait (or traits). Sexual selection may be directional, stabilizing, or disruptive. </li></ul>
  16. 20. Sexual Selection
  17. 21. Evolving New Species <ul><li>Speciation : The evolution of a new species. </li></ul><ul><ul><li>In order for speciation to occur, populations (or segments of populations) must become reproductively isolated. </li></ul></ul><ul><ul><li>There are 3 ways that a population can become reproductively isolated. </li></ul></ul>
  18. 22. Reproductive Isolation <ul><ul><li>Behavioral Isolation ; Occurs when two populations are physically capable of interbreeding, but have different reproductive behaviors. </li></ul></ul><ul><ul><li>Geographic Isolation : Occurs when a physical barrier (mountain, lake, etc.) separates two populations. </li></ul></ul><ul><ul><li>Temporal Isolation : Occurs when populations are capable of interbreeding, but each breed at different times. </li></ul></ul>
  19. 23. Behavioral Isolation Courtship rituals, like these, are critical for mating within a species, but ineffective for attracting members of other species.
  20. 24. Geographic Isolation
  21. 25. Geographic Isolation
  22. 26. Temporal Isolation
  23. 27. Convergent and Divergent Evolution <ul><li>Convergent Evolution : Two unrelated species develop similar traits due to similar environments. Convergent evolution causes Analogy . </li></ul><ul><li>Divergent Evolution : Two similar species develop differences due to different environments. Divergent Evolution causes Homology . </li></ul>
  24. 28. Genetic Drift <ul><li>Change in the frequency of alleles due to natural disasters. </li></ul><ul><li>Example: tornado, hurricane, flood… </li></ul>