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Natural Selection & Evidence for Evolution

Natural Selection & Evidence for Evolution. Notes 15.1. Evolution – change in a populations genetic makeup that takes place over many generations Species – group of organism that can interbreed and produce fertile offspring

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Natural Selection & Evidence for Evolution

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  1. Natural Selection & Evidence for Evolution Notes 15.1

  2. Evolution – change in a populations genetic makeup that takes place over many generations • Species – group of organism that can interbreed and produce fertile offspring • Members of species may share similar characteristics but variations exist among members (meiosis is a source of variation

  3. Charles Darwin • 1809-1882 • Born in England • Educated at Cambridge; degree in theology • Naturalist on HMS Beagle at age 21 • Voyage lasted five years (1831-1836)

  4. Observations • Collected biological specimens • On Galapagos Islands, Darwin observed species with similarities but unique differences from those elsewhere

  5. Figure 15–1 Darwin’s Voyage

  6. Giant Tortoises of the Galápagos Islands Pinta Tower Marchena Pinta IslandIntermediate shell James Fernandina Santa Cruz Isabela Santa Fe Hood Island Saddle-backed shell Floreana Hood Isabela Island Dome-shaped shell

  7. Hypothesis • Species change over time • How does it occur?

  8. Jean Baptiste Lamarck – first person to claim that species changed over time and could go extinct • first idea – use and disuse – claimed that body parts used regularly by organisms grow stronger and larger. Ie giraffes’ neck • second idea – acquired characteristics can be passed down from parent to offspring

  9. Figure 15–7 Lamarck’s Theory of Evolution

  10. Experiment/Gather evidence • Collecting & studying more specimens • Reading & studying • Malthus (economist) - populations increase faster than food supply • Organisms must compete for food & space in order to survive • Conducting experiments: pigeon breeding

  11. Conclusions • Darwin developed the Theory of Evolution by Natural Selection

  12. Theory of natural selection: • Organisms best suited to their environment as a result of favorable characteristics survive and reproduce

  13. Publish • 1858 - Alfred Russel Wallace formed similar conclusions • 1858 - Wallace & Darwin jointly presented conclusions to scientific community • 1859 - Darwin published On the Origin of Species by Natural Selection

  14. Theory • Further evidence led to acceptance of theory by the scientific community.

  15. Evidence of Evolution • Adaptations - inherited variations that improve an organism’s chance of survival • Structural • Mimicry: one species resembles another • Camouflage: species blends with surroundings • Physiological - changes in metabolic processes • Bacterial, insect, or weed resistance

  16. Evidence of Evolution • Fossil record • Record of early life, although incomplete • Biochemistry • DNA & RNA comparisons establish relationships between species

  17. Evidence of Evolution • Anatomy • Structural or functional similarities • With common origin (homologous structures) • Without common origin - common adaptations to similar circumstances (analogous structures) • Structure that no longer has a function (vestigial structures)

  18. The fossil record Geographic distribution of living species Homologous body structures Similaritiesin early development Physical remains of organisms Common ancestral species Similar genes Similar genes Concept Map Evidence of Evolution includes which is composed of which indicates which implies which implies

  19. Figure 15–14 Geographic Distribution of Living Species Beaver Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara NORTH AMERICA Muskrat Capybara SOUTH AMERICA Coypu

  20. Figure 15–15 Homologous Body Structures Turtle Alligator Bird Mammal Ancient lobe-finned fish

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