1 / 66

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)

ferguson-gavan
Download Presentation

EVOLUTION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related