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Evolution PowerPoint Presentation

Evolution

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Evolution

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  1. Evolution

  2. Evolution • What is evolution? • It is the process of biological change by which descendents come to differ from their ancestors

  3. Scientists • Scientists who began studying evolution: • Linnaeus (1700’s) • Developed classification system of organisms • Proposed that organisms arose from hybridization

  4. Scientists • Buffon (1700’s) • Used evidence of past life • Proposed that species shared ancestors instead of arising separately • Proposed earth was much older than 6000 years

  5. Scientists • Erasmus Darwin (1731) • Proposed all living things were descended from a common ancestor • Later expanded upon by his grandson

  6. Scientists • Lamarck (1809) • Didn’t believe in extinction • Species evolved instead • Proposed that changes in environment caused behavior to change • Organism passes on these traits to offspring • “Inheritance of acquired characteristics”

  7. Charles Darwin • Darwin took a trip to the Galapagos Islands aboard the HMS Beagle • He studied the inhabitants of the island

  8. What did Darwin find?

  9. Charles Darwin • Findings and conclusions: • Variation among species • Led him to believe species adapt to their environment • Adaptation- feature allows an organism to better survive in an environment • Leads to change in populations over time

  10. Examples of Adaptations

  11. horned lizard pistol shrimp aye aye archer fish

  12. Charles Darwin • Natural Selection • Individuals inherit beneficial adaptations and produce more offspring than others

  13. Charles Darwin • 4 principles of natural selection: 1. Variation - Differences among organisms 2. Overproduction - More offspring increases chance for survival 3. Adaptation - Certain variations allow to survive better 4. Descent with Modification - Over time, more individuals in the population will have the beneficial traits

  14. Natural Selection Variation Overproduction Descent with Modification Adaptation

  15. Fossil Evidence • No fossil evidence that contradicts evolution has been found • Allows us to see transitions of species over time

  16. Anatomical Evidence • Homologous structures • Features that are similar in structure, but different in function in different organisms • Supports common descent

  17. Anatomical Evidence • Analogous structures • Structures that perform similar function

  18. Anatomical Evidence • Vestigial structures • Unused features • Structure had a function in early ancestor • Helps support common ancestry and evolution

  19. Molecular Evidence • All living things have DNA • Organisms carry pseudogenes • Genes that do not function (vestigial) • Cells have very similar proteins • Marine worms have same proteins in the eye as vertebrates • Comparison of milk protein in whales and hippos: • Hippo TCC TGGCA GTCCA GTGGT • Humpback Whale CCC TGGCA GTGCA GTGCT

  20. Match the structureHomologous, analogous, or vestigial B A C

  21. Population Distributions • Normal Distribution • Frequency of a certain phenotype is near the mean

  22. Population Distributions • Directional Selection • Selection favors phenotypes at one extreme • Population shifts toward advantageous trait

  23. Population Distribution • Stabilizing Selection • The intermediate is favored and becomes the most common

  24. Population Distribution • Disruptive Selection • Both extreme phenotypes are favored

  25. Genetic Drift • Bottleneck Effect • Occurs after an event greatly reduces the size of a population • Ex. Overhunting of elephant seals

  26. Genetic Drift • Founder Effect • Occurs after a small # of individuals colonize a new area • Ex. Emerald ash borer

  27. Sexual Selection • Occurs when certain traits increase mating success • Two types: • Intrasexual • Physical competition among males • Intersexual • Displays among males • Examples: • Intrasexual • Intersexual Bird display Giraffe fight

  28. Long-tailed Widowbird Male Female

  29. Evolutionary Classification • Cladogram • Evolutionary tree that proposes how species may be related to each other through common ancestors • Clade • Group of organisms that share certain traits

  30. Evolutionary Classification Cladogram for modes of transportation: Bicycle Car Motorcycle Airplane On foot walking bicycle motorcycle car airplane wings Passengers enclosed motor wheels