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EVOLUTION

EVOLUTION. “Change over time”. Lamarck is Silly. Simpson’s season 17. Change over time. Change in populations of a species - Not a change in individuals You as an individual can not evolve – your DNA never changes (although you do develop)

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EVOLUTION

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  1. EVOLUTION “Change over time”

  2. Lamarck is Silly

  3. Simpson’s season 17

  4. Change over time • Change in populations of a species - Not a change in individuals • You as an individual can not evolve – your DNA never changes (although you do develop) • Time = Multiple generations … often this means significantly LONG periods of time

  5. Lamarck • Inherit acquired characteristics • Sometimes called the Law of use /disuse

  6. Charles Darwin • Descent with modification • A “tree” of life • Theory of Natural Selection

  7. Charles Darwin • Was not an atheist (his father was a pastor and he studied to be clergyman himself) • Was not the first to write about evolution (His grandfather had also written about evolution) • Spent five years studying wildlife in South America aboard the HMS Beagle

  8. The Galapagos Finches

  9. The Galapagos Finches

  10. Natural Selection 1. Overproduction 2. Variation within a species 3. Competition “survival of the fittest” 4. Differential reproduction

  11. Over reproduction • Observation 1: Left unchecked, the number of organisms of each species will increase exponentially, from generation to generation. • Example: Exponential Kitten

  12. Example: Exponential Kitten • Every day, this kitten will reproduce by splitting. The total number of kittens will double each day. • Day One, One Kitten

  13. Example: Exponential Kitten • Day Two, Two Kittens.

  14. Example: Exponential Kitten • Day Three, Four Kittens

  15. Example: Exponential Kitten • Day Four, Eight Kittens.

  16. Example: Exponential Kitten • Day Five, Sixteen Kittens.

  17. Example: Exponential Kitten • Day Six, Thirty-Two Kittens.

  18. Example: Exponential Kitten • Day Seven, Sixty-Four Kittens.

  19. Example: Exponential Kitten Day Eight, 128 kittens

  20. Exponential Growth Day 1-1cent Day 2 - 2cents Day 3 -4cents Day 4-8cents Day 5-16cents Day 6-32cents Day 7-64cents Day 8-$1.28 Day 9-$2.56 Day 10 - $5.12 Day 11 – $10.24 Day 12 - $20.48 Day 13 – 40.96 Day 14 – 81.92 Day 15 -163.84 Day 16 - $327 Day 17 - $655 Day 18 - 1310 Day 19 – 2620 Day 20 - 5240 Day 21 - 10,480 Day 22- 20,960 Day 23-41,920 Day 24 – 83,840 Day 25 – 167,680 Day 26 – 335,360 Day 27 – 670,720 Day 28 – 1,341,440

  21. Key Terms for Evolution • Adaptation: An inherited characteristic that increases an organism’s ability to survive and reproduce in its specific environment. • Fitness: The ability to survive and reproduce in a specific environment. Adaptations make an organism more fit.

  22. “Fitness” Unique to a particular environment

  23. Fitness • ‘Survival of the most fit’ does NOT equal survival of the strongest, fastest, smartest, etc….. • It means best adapted to its environment

  24. Key Terms for Evolution • Descent with Modification: Over long periods, natural selection produces organisms that continually adapt to their environment, eventually becoming separate species. • Each living species has descended, with changes, from other species over time. • Artificial Selection: Nature provides the variation and human select those variances they find useful. • Example: a farmer breeds only his best livestock.

  25. Evolution Evidence of Change

  26. To be considered science, a theory requires a great deal of evidence

  27. Proof of Evolution • Fossils • Biogeography • Homologous Structures • Vestigial Structures • Embryonic Development • Comparative DNA

  28. The Fossil Record • Fossils: Evidence of former life. Provides information about past organisms • Shows that many diverse organisms lived at different times in Earth’s History

  29. FOSSILS • 99.99999999% of organisms DO NOT become fossils • Most organisms decompose when die • To become a fossil – a dead organism needs to preserved in an environment without decomposers… rock, tar, amber, etc…

  30. Fossils • “Evidence” of former life can also include preserved nests, footprints/tracks, coprolites, etc….

  31. Determining the Age of Fossils • Relative Dating: Determine the age of fossils relative to fossils in other layers of rock • Different layers “strata” represent different geologic periods • In general, older fossils found in lower layers, newer fossils found in upper layers • Cannot determine the actual age of the fossil!

  32. Determining the Age of Fossils • Radioactive Dating: Traces of radioactive elements are used to calculate the actual age of a fossil • Each radioactive element decays at its own nearly constant rate. • YOU have radioactive elements inside your body!

  33. Archaeopteryx “Missing Links”

  34. Homologous Structures Flying Swimming Running Grasping

  35. Comparative Embryology • Embryos are organisms at early stages of development

  36. Embryology At EARLY age of development much similarity – You once had gill slits

  37. Comparative Biochemistry • All life is based on organic chemistry • Carbon based compounds • All life uses same molecule as blueprint ….. DNA • Similar structures (organelles) • Similar organisms have similar genetic code • Humans and chimpanzees share nearly identical genes (98.4% identical gene sequences)

  38. Vestigial Organs • Organs inherited but not used by modern organisms • We believe that our ancestors used the organ in a more developed form • Examples: Hip bone in python, Appendix in human, Tail bone (cocyx) in human

  39. Genetic Change: Key Terms • Gene: Particular parts of DNA that results in traits. • Gene Pool: The combined collection of genes for all traits in a population. • Genetic Equilibrium: Occurs when the gene frequencies are stable from generation to generation • Bell Curve: The shape of a graph depicting a “normal” distribution of genes

  40. Gene Pool • Gene Pool: The combined collection of genes for all traits in a population.

  41. Natural Selection and Genetic Equilibrium • Natural Selection can affect a Gene Pool (and Bell Curve) in 3 ways. • Directional Selection: Individuals at one end of the curve have higher fitness than those in the center or at the other end. • Stabilizing Selection: Individuals near the center of the curve have higher fitness than those at either end. • Disruptive Selection: Individuals at both end of the curve have higher fitness than those in the center.

  42. Three Forms of Natural Selection

  43. Flash • If Lions in Africa are unable to attack the largest elephants, what kind of natural selection will occur? • A: Stabilizing • B: Directional • C: Disruptive

  44. Flash • Fashion writers publish an article saying that the fur from small rabbits is too fine, while that from large rabbits is too coarse. Trappers now want only average rabbits. • A: Stabilizing • B: Directional • C: Disruptive

  45. Flash • In a school of fish, those that are too big stand out, while those that are too small struggle to keep up. As a result, the largest and smallest fish are eaten. • A: Stabilizing • B: Directional • C: Disruptive

  46. Sexual Selection • 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.

  47. Sexual Selection

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