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Objective 6 Notes

Objective 6 Notes. Evolution, Natural Selection & Adaptations. 1. Vocab. Evolution A genetic change in a population over time Note: individuals do not evolve, only populations show change Theory A well supported explanation of a scientific phenomenon Fitness

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Objective 6 Notes

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  1. Objective 6 Notes Evolution, Natural Selection & Adaptations

  2. 1. Vocab • Evolution • A genetic change in a population over time • Note: individuals do not evolve, only populations show change • Theory • A well supported explanation of a scientific phenomenon • Fitness • The ability of an organism to survive and reproduce in a given environment

  3. 2. Charles Darwin • From 1831-1836, a young naturalist called Charles Darwin toured the world in HMS Beagle. • Where food was limited, competition meant that only the fittest would survive. • This would lead to the natural selection of the best adapted individuals

  4. 3. Assumptions of the Evolutionary Theory • The earth is billions of years old • Time + small changes = large changes • Mutations can be beneficial

  5. 3. Natural Selection • The process by which individuals that are better suited to their environment survive and reproduce most successfully • Also called: • Survival of the Fittest • Artificial Selection

  6. 3. Natural Selection • Types

  7. 4. Mechanisms of Evolution • Genetic Variation • Mutations • Meiosis (crossing over) • Natural Selection • Reproductive Isolation

  8. 5. Evidence of Evolution • Fossil Records • Homologous Structures • Analogous Structures • Vestigial Structures • DNA

  9. Fossil Record • Fossils are preserved evidence of dead organisms • Assumes that it takes a long time for sediment to accumulate • Assumes that the dead organism had offspring • Assumes that there are millions of years separating each sediment layer.

  10. Homologous Structures • Structures that have a similar structure (anatomy) from one organism to another. • Example: limbs • Human leg v. Whale flipper • Both contain bones called femur, tibia, fibula, etc. • Similar structure but different functions

  11. Analagous Structures • Structures that have a similar function (physiology) but different structure between organisms. • Example: Wings • Butterfly wing v. Bird wing • Both enable flight, but are very different structures

  12. Vestigial Structures • Defined as a structure that serves no useful function in an organism. • Most common citations of this are not accurate: • Coccycx: without it humans cannot pass solid waste. • Appendix: might have immune/lyphatic functions • Tonsils: have immune and lyphatic functions • Eyebrow/lash: keeps sweat/dust/particles out of eyes • Body Hair: mechanoreceptors at base, traps heat, offers protection from sun rays

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