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Evolution

Evolution. Fossil Records Remains or traces of organisms that lived in the past Usually found in sedimentary rocks. Evolution . Organism buried soon after death and the hard parts become fossilized

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Evolution

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  1. Evolution • Fossil Records • Remains or traces of organisms that lived in the past • Usually found in sedimentary rocks

  2. Evolution • Organism buried soon after death and the hard parts become fossilized • Fossils indicate a great deal about the actual structure of the organisms and their environment

  3. Evolution • Types of Fossils • petrified bones • imprints • molds • preserved in tar, amber, or ice

  4. Evolution • Dating of fossils • Layering of fossils • Older fossils are found in the lower levels of sediment • Carbon-14 Dating • Carbon-14 is a radioactive isotope in all living organisms. • It decays at a known rate • Carbon-12 does not decay • Compare ratio of C-12 to C-14 to determine age

  5. Evolution • Contemporary changes • DDT resistance in insects • Antibiotic resistance in bacteria • Indirect Evidences • Evidences of common ancestry • Parts of the body with similar (homologous) structures

  6. Evolution • Indirect Evidences • Similar patterns of inheritance • Biochemical Similarities (protein and DNA) • Vestigial organs

  7. The Methods of Change • Lamarck’s Theory – 1809 • “Inner need” to change • Inheritance of acquired characteristics (based on use and disuse) • Disproved

  8. The Methods of Change • Charles Darwin and Natural Selection - (1859) • Naturalist on HMS Beagle • Exploration of South America (3 ½ years) • Visited the Galapagos Islands

  9. The Methods of Change • Natural Selection • Living things increase in number geometrically - (overproduction) • There is no net increase in the number of individuals over a long period of time • A “struggle for existence” exists since not all individuals can survive

  10. The Methods of Change • Natural Selection • No two individuals are exactly alike (variation) • In the struggle for existence those variations which are better adapted to their environment leave behind them proportionately more offspring than those less adapted - (Survival of the Fittest)

  11. The Methods of Change • A Modern Perspective • Mutation • A sudden change in the genetic material (A source of variation) • Recombination of genes within a population • Provides new combinations for natural selection • Shows how the percentage of genes in a population can change

  12. The Methods of Change • A Modern Perspective • Isolation • Separation of a population from others of the same kind • Natural Selection • Certain traits give an adaptive advantage to organisms and they leave more offspring

  13. Species • A group of individuals that LOOK similar and are capable of producing FERTILE offspring in the natural environment.

  14. Population • All of the members of the same SPECIES that live in particular AREA at the same TIME.

  15. Variation in a population • Bell Curve • The distribution of traits (Average is the middle.) • Mode • The number that occurs most often (High pt.) • Range • The lowest number to the highest number

  16. Gene Pool • The collection of GENES for all of the traits in a POPULATION

  17. Hardy-Weinberg Principle • Genetic Equilibrium • No CHANGE in the gene pool

  18. Conditions that must exist for genetic equilibrium 1. No MUTATION 2. No MIGRATION 3. Large POPULATION 4. Random MATING 5. No NATURAL SELECTION

  19. Natural Selection Four types of selection 1. Stabilizing Selection 2. Directional Selection 3. Disruptive Selection 4. Sexual Selection

  20. Stabilizing Selection • Individuals with the AVERAGE form have the ADVANTAGE

  21. Directional Selection • Individuals with one of the EXTREME forms have the ADVANTAGE

  22. Disruptive Selection • Individuals with either of the EXTREME forms have the ADVANTAGE

  23. Sexual Selection • Preferential choice of a MATEbased on the presence of a specific trait

  24. Speciation • The formation of new SPECIES

  25. Isolation • Separation of a formerly successful BREEDING population

  26. Geographic Isolation • Separated PHYSICALLY from each other

  27. Reproductive Isolation • Can no longer produce FERTILE offspring

  28. Extinction • When an entire SPECIES dies off.

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