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Evidence of Evolution

Evidence of Evolution

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Evidence of Evolution

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  1. Evidence of Evolution • This PowerPoint was revised Jan 1, 2010 for Unique



  4. On his journey around the world, Darwin found evidence of gradual change (evolution). Darwin cited evidences he found in fossil records, geographic distribution and homologous structures. Charles Darwin

  5. Today most evidences for evolution are grouped into five main categories: Biochemical Fossil Record Comparative Anatomy Biogeography Observable Events Evidences of Evolution

  6. Paleontology Fossil – remains or traces of an organism that lived long ago Remains: ex. bone, tooth, or shell Traces: ex. burrow, footprint, or imprint FOSSIL RECORD

  7. Most fossils are found in layered sedimentary rock Oldest fossils are on the lowest layer FOSSIL RECORD

  8. Comparing fossils from different layers shows: Life on Earth has changed Increased number of life forms FOSSIL RECORD

  9. THE GENETIC CODE Triplets of DNA nitrogen-base sequences that code for specific amino acids The amino acid triplet is the same in almost all organisms. BIOCHEMICAL

  10. The similarity of triplet DNA codes making-up amino acids shows: A probable common ancestor for all life on Earth BIOCHEMICAL

  11. “Universal” GENETIC CODE Similar genes Over the ages, the genetic code has passed unchanged (or nearly so) from parent to offspring. BIOCHEMICAL

  12. AMINO ACID SEQUENCING The amino acid sequence in a particular protein is compared between organisms. 125 45 1 67 8 27 BIOCHEMICAL Number of differences from human hemoglobin

  13. Comparing amino acid sequence shows: Closeness of relationship A probable common ancestor BIOCHEMICAL Amino Acid Difference in Hemoglobin Compared with Human Amino Acid Sequencing is probably the STRONGEST evidence for relationships among organisms. Human hemoglobin has 146 amino acids

  14. Amino Acid Difference in Hemoglobin Compared with Human CLADOGRAM: diagram that shows the evolutionary relationship among a group of organisms. 100 20 150 50 0 40 30 10 Number of Amino Acid Differences BIOCHEMICAL B A C D Where would the common ancestor be? What organism belongs at each branch? E F G Common ancestor

  15. HOMOLOGOUS STRUCTURES structures with similar structure but different function (ex: turtle, alligator, bird, mammal) Alligator Turtle Bird Mammal COMPARATIVE ANATOMY

  16. Homologous structures show Similar genes Descent from a common ancestor Alligator Turtle Bird Mammal Ancient lobe-finned fish COMPARATIVE ANATOMY

  17. VESTIGIAL STRUCTURES organs so reduced in size that they are nonfunctioning remnants of similar organs in other species ex: human tailbone, appendix, whale pelvis COMPARATIVE ANATOMY

  18. Vestigial structures show: an organism’s evolutionary past a common ancestor with species that have similar structures that are still functioning COMPARATIVE ANATOMY

  19. Analogous Structures COMPARATIVE ANATOMY • Unrelated species have evolved to have similar adaptations

  20. EMBRYOLOGY Embryos of different species may appear similar in early stages of development ex: vertebrate development COMPARATIVE ANATOMY

  21. Comparison of similarities in embryos can show: Relationship to a common ancestor COMPARATIVE ANATOMY

  22. GEOGRAPHIC DISTRIBUTION OF ORGANISMS organisms living widely apart (even different continents) may be similar because they share a common ancestor Beaver Muskrat Beaver andMuskrat Coypu Capybara Coypu andCapybara BIOGEOGRAPHY • Shows common ancestor

  23. Some changes in species have been observed and studied: OBSERVABLE EVENTS

  24. Observable events show that evolution is an ongoing process OBSERVABLE EVENTS

  25. Works Cited • Miller, Kenneth and Levine, Joseph. (2004). Biology. Prentice Hall.