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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 From, Darwin’s , 1839, “Birds Part 3 No. 3 of The zoology of the voyage of H.M.S. Beagle.: illustration by John Gould From Darwin’s “Transmutations of Species,” 1837. The first family tree Charles Darwin

  2. The Fossil Record 1) Shows which organisms once existed • 99.9% of all species that ever existed are now extinct Trilobytes – 405 million years ago The oldest fossil record of multicellular life, filaments of Bangiomorpha, a red algae, are 1.6 billion years old

  3. Fission-track Paleomagnetic Potassium/Argon and Argon/Argon Uranium Series Dating method Thermoluminescence Amino Acid Racemization Radiocarbon 0 1 2 3 4 5 Electron Spin Resonance mya 2) Indicates when the organisms existed • radiometric dating is used to determine age of fossils

  4. 3) Shows a logical sequence of forms • invertebrates • fish • amphibians • reptiles • mammals and birds Pterodactyl then Bird

  5. 4) Shows transitional forms between species Transitional Forms – fossils or organisms that show intermediate states between an ancestral form and that of its descendants There are numerous examples of transitional forms in the fossil record

  6. Pakicetus was a land mammal, Aetiocetus a transitional species, and the gray whale a modern species

  7. Transitional stages occur between modern horses (Equus) and the four-toed Hyracotherium

  8. There are 3 elephant species living today. The fossil record shows that 350 species used to exist

  9. Eupodophis – lived 92 million years ago and had legs; it’s a transitional form between lizards and limbless snakes

  10. Comparative Anatomy Shows evolutionary relationships between groups • homologous structures – similar structures because of • common descent

  11. Whales and hummingbirds have tetrapod skeletons inherited from a common ancestor. Their bodies have been modified and parts have been lost through natural selection. On the surface, these animals look very different, but the relationship between them is easy to see

  12. Frogs, birds, rabbits and lizards all have different forelimbs, reflecting their different lifestyles. But those different forelimbs all share the same set of bones - the humerus, the radius, and the ulna. These are the same bones seen in fossils of the extinct transitional animal, Eusthenopteron, which demonstrates their common ancestry

  13. Comparative Embryology • closely related organisms go through • similar stages in their embryonic • development Embryology – the study of embryo development Ontogeny – the development of an organism from egg to adult form

  14. Similarities/differences in ontogeny • help establish evolutionary • relationships (phylogeny) • Phylogeny – the evolutionary history of a group • of organisms

  15. Early embryos of many different vertebrate • species look remarkably similar

  16. note that human embryos have similar blood • vessel structure as a shark

  17. Molecular Biology • evolutionary relationships are reflected in the • DNA and proteins of organisms; closely • related organisms have similar DNA • sequences

  18. Comparison of mammalian genomes, using either whole genomes or just • introns, Sung-Hou Kim lab/UC Berkeley

  19. Mutations occur at a fairly predictable rate. • Therefore, the similarity/differences in base • sequences of DNA reveal the evolutionary • history of species nucleotide substitutions among 17 mammal species from seven gene products versus time of divergence according to fossil records

  20. Mutation rates • bacteria 10-8 /bp/generation • DNA Viruses 10-6 to 10-8/bp/generation • eukaryotes 10-4 to 10-6/bp/generation • humans 4.8 x 10-9 /bp/generation * bp = base pairs

  21. changes in the base sequences of SARS virus • show relationships between various strains of the • virus, and shows that the virus “jumped” from bats • to civets (a cat) and humans

  22. Evolutionary tree of HIV-1 shows how the virus hopped from chimpanzee hosts to humans. HIV-1 is most closely related to the SIV virus that infect chimps

  23. There are about 100 breeds of domestic cats. All originated from the African Wildcat, Felis sylvestris. Modern cats appear to have originated in Asia 10 million years ago.

  24. Biogeography • the geographic distribution of species • suggests evolutionary relationships Biogeography – the study of the geographic distribution of species

  25. The marsupials of Australia are thought to have migrated from South America and across Antarctica to Australia (arrow) by way of land bridges, some 70 million years ago