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Evolution Evidence

Evolution Evidence. Chapter 22 Part 2 – Revised AP Bio. Questions (Page 1 of 2). 1. What is evolution? 2. What is the dominant (most common mode) of evolution? 3. Can evolution arise without natural selection?

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Evolution Evidence

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  1. Evolution Evidence Chapter 22 Part 2 – Revised AP Bio.

  2. Questions (Page 1 of 2) • 1. What is evolution? • 2. What is the dominant (most common mode) of evolution? • 3. Can evolution arise without natural selection? • 4. Name 2 purposeful mechanisms of evolution that do not include natural selection.

  3. Questions (Page 2 of 2) • 5. Name 2 “random” mechanisms of evolution. • 6. How do individuals evolve resistance to bacteria or viruses? • 7. Name 2 sources of evidence for evolution. • 8. What are the 2 principles that underlie natural selection? • 9. How does microevolution differ from macroevolution?

  4. Evidence for Evolution • Direct observation of Evolutionary change • Antibiotic-resistant bacteria & drug-resistant virus populations • The Fossil Record • Paleontology – study of fossils • Fossils show that evolutionary changes have occurred over time • Punctuated equilibrium instead of gradualism • Long periods of stasis punctuated by brief bursts of evolutionary activity

  5. Evidence for Evolution (Page 2) • Homology and Convergent Evolution • Homology – structural similarity resulting from common ancestry • Homologous structures – anatomical signs of evolution • Embryonic homologies • Early stages of animal development reveal many anatomical homologies that are not present in the adult form • In vertebrates, Ontogeny recapitulates Phylogeny

  6. Anatomical Homologies

  7. Ontogeny recapitulates Phylogeny

  8. Evidence for Evolution (Page 3) • Vestigial organs • Structures of dubious utility • Remnants of previously important structures • Appendix (humans) • Limb remnants (snakes)

  9. Evidence for Evolution (Page 4) • Molecular homologies • Homologies at the molecular level • Everything uses DNA & RNA • Humans & Chimps – 99% same DNA (bonobos = 98.7%) • Amino acid sequences in hemoglobin in primates is extremely similar (common ancestor) • Convergent Evolution • Two organisms develop similarities as they adapted to similar environments • Analogous structures result, not homologous

  10. Stingrays – were dorsoventrally flattened, so they lie on their belly •  Note the midline location of the “backbone” column • Flounders – laterally flattened, so they lie on their sides •  Note the vertebral column on the right

  11. Homology v. Analogy • Homologous structures show evidence of relatedness • Whale fin/Bat wing • Analogous structures show similar solutions to similar problems, but do NOT indicate relatedness • Ray and flounder ventral orientation

  12. Biogeography • The geographical distribution of a species • Closely related species tend to be found in the same geographical region • Continental drift – breakup of pangaea • Can explain species similarity in disparate geographic regions • Endemic species • Species found in one geographic location and nowhere else • Example: marine iguanas in Galapagos

  13. Artificial Selection • Human controlled selecting and breeding of organisms to produce desirable traits (for humans) • Selective breeding of domesticated plants and animals influenced Darwin’s thinking • Crop plants and animals often bear little resemblance to their wild ancestors • Artificial selection can change much in a short period of time. Natural selection may be able to do so as well

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