Principles Evolution APBioCh13-14


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  • Principles Evolution APBioCh13-14

    1. 1. Principles of Evolution
    2. 2. Evolution of Evolutionary Thought <ul><li>Develop time line of historical events </li></ul><ul><ul><li>427-347 B.C. Plato’s divinely inspired “ideal form” </li></ul></ul><ul><ul><li>384-322 B.C. Aristotle’s “Ladder of Nature” </li></ul></ul><ul><ul><li>until 1700s Creationism </li></ul></ul><ul><ul><ul><li>Each species was created individually by God </li></ul></ul></ul><ul><ul><ul><li>Earth was the center of the universe </li></ul></ul></ul><ul><ul><ul><li>Man stood atop creation </li></ul></ul></ul><ul><li>Exploration of New Lands </li></ul><ul><li>Number of species was greater than expected </li></ul><ul><li>Some species closely resembled one another </li></ul><ul><li>Some naturalists concluded that similar species may have developed from a common ancestor </li></ul>
    3. 3. Evolution of Evolutionary Thought I <ul><li>1707-1788 George LeClerc (Comte of Buffon); </li></ul><ul><li>creation provided a relatively small number of founding species that evolved through natural processes </li></ul><ul><li>Idea was not accepted </li></ul><ul><ul><li>Did not provide a mechanism for evolution </li></ul></ul><ul><ul><li>Earth was not old enough to allow time for the process of evolution </li></ul></ul><ul><li>1769-1832 G. Cuvier; theory of catastrophism (creationist w/extinction) </li></ul>
    4. 4. Evolution of Evolutionary Thought III <ul><li>1726-1797 James Hutton developed uniformitarianism – gradual change </li></ul><ul><li>1797-1875 Charles Lyell’s “Old Earth Hypothesis” supported Hutton, gave time for gradual change </li></ul><ul><li>(Archbishop James Ussher calculated the date of the creation of the Earth…Oct 23, 4004BC…using biblical lineages.) </li></ul><ul><li>1744-1829 Jean Baptiste de Lamarck - inheritance of acquired characteristics (‘cuz if you are gonna be wrong…do it spectacularly!’) </li></ul>
    5. 5. Evolution of Evolutionary Thought IV <ul><li>1809-1882 Charles Darwin </li></ul><ul><ul><li>Developed the theory of evolution </li></ul></ul><ul><ul><ul><li>Species evolved through natural selection; </li></ul></ul></ul><ul><ul><ul><li>Adaptation to their ever-changing environment. </li></ul></ul></ul><ul><li>1823-1913 Alfred Wallace; supported Darwin's theory (worked separately, came up with same conclusion, came in “2 nd” ) </li></ul><ul><li>Present theory of evolution by natural selection </li></ul>
    6. 6. Darwin’s Finches
    7. 7. A Flowchart of Evolutionary Reasoning EVOLUTION: The genetic makeup of the population changes over time, driven by natural selection NATURAL SELECTION On average, the fittest organisms leave the most offspring Competition for survival and reproduction Potential for rapid reproduction Relatively constant resources and population over time Variability in structures and behaviors Some variability is inherited (observations) (conclusions)
    8. 8. Evolution by Natural Selection <ul><li>Postulate 1: Individual members of a population differ from one another in many respects </li></ul><ul><ul><li>Variations arise purely by chance resulting from random mutations in DNA </li></ul></ul><ul><ul><li>Differences are obvious in many physical characteristics and extend to molecular level </li></ul></ul>
    9. 10. Evolution by Natural Selection <ul><li>Postulate 2: At least some of the differences among members of a population are due to characteristics that may be passed from parent to offspring </li></ul><ul><ul><li>However, the mechanism of inheritance was not understood at this point in time (Mendel was working at about the same time…and was ignored until someone saw that Mendel and Darwin/Wallace supported each other.) </li></ul></ul>
    10. 11. Evolution by Natural Selection <ul><li>Postulate 3: In each generation, some individuals in a population survive and reproduce successfully but others do not </li></ul><ul><ul><li>Darwin observed that many more individuals are born than survive </li></ul></ul><ul><ul><li>Some individuals have more offspring than others </li></ul></ul>
    11. 12. Evolution by Natural Selection <ul><li>Postulate 4: Individuals with advantageous traits survive longest and leave the most offspring, a process known as natural selection </li></ul>
    12. 13. Evolution by Natural Selection <ul><li>Gregor Mendel’s theories of inheritance (1865) confirmed Darwin’s assumption that certain traits are heritable </li></ul><ul><li>New variations arise by chance as a result of random mutations in DNA </li></ul><ul><li>New variations may be good, bad, or neutral </li></ul>
    13. 14. Populations Evolve <ul><li>Natural selection acts on individuals within a population; however, it is the population that changes over time </li></ul>
    14. 15. Evidence of Evolution: Fossils <ul><li>Transitional forms are evidence of evolutionary change </li></ul><ul><li>Fossils of ancient species tend to be simpler in form than modern species </li></ul><ul><li>Several series of fossils have been found that exhibit the evolution of body structures over time </li></ul><ul><li>Interpretation of fossil data controversial </li></ul><ul><ul><li>Dating of fossils </li></ul></ul><ul><ul><li>Do fossils really show transitional forms? </li></ul></ul>
    15. 16. Information from Fossils?
    16. 17. Fossils of Extinct Organisms
    17. 18. Evidence of Evolution: Comparative… <ul><li>…Anatomy </li></ul><ul><ul><li>Homologous structures </li></ul></ul><ul><ul><ul><li>structures that have the same evolutionary origin despite their current appearance or function </li></ul></ul></ul><ul><ul><li>Analogous structures </li></ul></ul><ul><ul><ul><li>structures that are outwardly similar in appearance, but differ in their evolutionary origin </li></ul></ul></ul><ul><ul><li>Vestigial structures </li></ul></ul><ul><ul><ul><li>remnants of structures that are inherited from ancestors </li></ul></ul></ul><ul><ul><ul><li>Had important functions in ancestors </li></ul></ul></ul><ul><ul><ul><li>Serve no obvious purpose in present day organism </li></ul></ul></ul>
    18. 19. Analogous Structures Not homologous; not analogous Homologous; not analogous Not homologous; analogous Homologous; analogous
    19. 20. Homologous Structures Flying Swimming Running Grasping
    20. 21. Vestigial Structures
    21. 22. Evidence of Evolution: Comparative… <ul><li>…Embryology </li></ul><ul><ul><li>Early vertebrate embryos similar </li></ul></ul><ul><ul><li>Tail and gill arches </li></ul></ul>
    22. 23. Comparative Embryology
    23. 24. Evidence of Evolution: Comparative… <ul><li>… Biochemistry & molecular biology </li></ul><ul><ul><li>All have DNA, RNA, ribosomes, ATP, etc. </li></ul></ul><ul><ul><li>DNA similarities </li></ul></ul>
    24. 26. How Organisms Evolve
    25. 27. Population Genetics and Evolution I <ul><li>Gene pools and allele frequencies </li></ul><ul><li>Evolution: Change in gene frequencies </li></ul><ul><ul><li>Due to differential reproduction among organisms bearing different alleles </li></ul></ul><ul><ul><li>Fitness of the selected allele leads to viable offspring </li></ul></ul><ul><ul><li>Evolutionary changes are not &quot;good&quot; or &quot;progressive&quot; in any absolute sense </li></ul></ul>
    26. 28. Population Genetics and Evolution II <ul><li>Natural selection causes changes in gene frequencies of a population </li></ul><ul><ul><li>Does not genetically change individuals! </li></ul></ul><ul><ul><li>Affects individuals, but evolution occurs in populations </li></ul></ul><ul><li>Mutations: Source of new alleles </li></ul><ul><li>Sexual reproduction produces new combinations of alleles </li></ul><ul><ul><li>Crossing over in meiosis </li></ul></ul><ul><ul><li>Random fertilization of gametes </li></ul></ul>
    27. 29. Mechanisms of Evolution I <ul><li>The hypothetical equilibrium population </li></ul><ul><ul><li>Hardy-Weinberg equilibrium </li></ul></ul><ul><ul><li>For a population to be at equilibrium, 5 conditions MUST be true… </li></ul></ul><ul><li>No Mutations </li></ul><ul><li>No Migration/Emigration (gene flow) </li></ul><ul><li>Large population size </li></ul><ul><li>Random Mating </li></ul><ul><li>No Natural Selection </li></ul><ul><li>…this would mean there is NO Evolution! </li></ul>
    28. 30. Genetic Drift
    29. 31. Genetic Bottlenecks Reduce Variability Chance loss of blue Time
    30. 32. Mechanisms of Evolution II <ul><li>Nonrandom mating and sexual selection </li></ul><ul><li>Natural selection </li></ul><ul><ul><li>Types of natural selection </li></ul></ul><ul><ul><ul><li>Directional selection </li></ul></ul></ul><ul><ul><ul><li>Stabilizing selection </li></ul></ul></ul><ul><ul><ul><li>Disruptive selection </li></ul></ul></ul>
    31. 33. Types of Natural Selection Large Size Favored Directional Selection Average Size Favored Stabilizing Selection Extreme Size Favored Disruptive Selection Variation reduced over time Mean changed over time Variation becomes polarized Before Selection After Selection Time
    32. 34. Forces of Natural Selection <ul><li>Abiotic factors (environmental changes!) </li></ul><ul><li>Biotic factors </li></ul><ul><ul><li>Coevolution - constant mutual feedback between two species </li></ul></ul><ul><ul><ul><li>Competition for limited resources </li></ul></ul></ul><ul><ul><ul><li>Predation </li></ul></ul></ul><ul><ul><ul><li>Symbiosis </li></ul></ul></ul><ul><ul><ul><li>Parasitism, commensalism, and mutualism </li></ul></ul></ul><ul><li>Altruism - self-sacrifice </li></ul>
    33. 35. Causes of Extinction <ul><li>Localized distribution (i.e. all in one place) </li></ul><ul><li>Overspecialization (i.e. can only eat one thing) </li></ul><ul><li>Environmental changes </li></ul><ul><ul><li>Competition for limited resources </li></ul></ul><ul><ul><li>Predators and parasites cause diseases </li></ul></ul><ul><ul><li>Habitat destruction </li></ul></ul><ul><ul><ul><li>Deforestation </li></ul></ul></ul><ul><ul><ul><li>Meteorites </li></ul></ul></ul><ul><ul><ul><li>Fires </li></ul></ul></ul><ul><ul><ul><li>Volcanic eruptions </li></ul></ul></ul>
    34. 36. Stabilizing Selection & Balance Polymorphism HH HH Hh Hh Hh hh hh hh Dies of malaria HH Lives and reproduces Dies of sickle-cell anemia Dies of malaria Lives and reproduces Dies of sickle-cell anemia Homozygous Normal Homozygous Defective Heterozygous
    35. 37. The end