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Evolution

Evolution. Lab 13. Theory of Evolution . Describes: Genetic change in populations. Evidences of Evolution. Evolution: process by which life has changed through time. There are different types of data that support the theory of evolution: Some are:

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Evolution

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  1. Evolution Lab 13

  2. Theory of Evolution • Describes: Genetic change in populations

  3. Evidences of Evolution • Evolution: process by which life has changed through time. • There are different types of data that support the theory of evolution: • Some are: • 1. fossil record 2. comparative anatomy • 3. molecular differences

  4. Fossils • Remains or evidence of some organism that lived long ago. • Can be used to trace the history of life on earth

  5. Comparative Study • Comparatived study of the anatomy of modern groups of organisms has shown that each group has strucutures of similar construction • Called Homologous structures • Example: all vertebrate animals have essentially same type of skeleton. • Homologous structures are theorized to signify relatedness through evolution.

  6. Molecular differences • Living organisms use the same basic molecules • Including ATP, DNA, proteins

  7. Evidence from the fossil Record • Geologic Timescale • Developed by both geologists and paleontologists • Depicts history of life based on the fossil record (page 230)

  8. Divisions of the Timescale • Timescale divides the proposed history of Earth into eras, then periods, and then epochs. • 4 eras span the greatest amounts of time, and the epochs are the shortest time frames.

  9. Note • Only the periods of the Cenozoic Era are divided into epochs • More attention is given to the evolution of primates and flowering plants than to the earlier evolving organisms

  10. Partner up and answer questions Page 315

  11. Dating within the timescale • Timescale provides both relative dates and absolute dates. • Ex: relative time: “flowering plants evolved during the Jurassic period” • Flowering plants evolved earlier or later than groups in other periods • Ex: absolute time: using dates that ar in millions of years (mya)

  12. Limitations of the timescale • Appears evolution occurred from cell to human • Not the case • Prokaryotes – bacteria and Achaea – never declined and are still most abundant and successful organisms on earth. • Constitute 90% of total weight of living things

  13. Extinction (still in limitations of time scale) • Timescale lists mass extinctions • Does not tell when specific groups became extinct. • Extinction – total disappearance of a species or a higher group • Mass extinction – occurs when a large number of species disappear in a few million years or less. • For lack of space: geologic timescale cant depict in detail what happened to members of every group mentioned. See figure 23.1

  14. Observation of Fossils • Page 232: Viewing fossils

  15. Evidence of Comparative Anatomy • Organisms or parts of organisms are said to be “homologous” if they exhibit similar basic structures and embryonic origins. • If similar in function only – said to be “analogous” • Only homologous structures indicate an evolutionary relationship and are used to classify organisms.

  16. Comparison of Adult Vertebrate Forelimbs • Page 234 • The limbs of vertebrates are homologous structures. • Homologous structures share basic pattern, although there may be specific differences. • Descent from a common ancestor

  17. Analyze bones and fill in Table 23.5 on page 234 • Vertebrate forelimbs

  18. Comparison of Chimpanzee & Human Skeletons • Bones are closely related • Examine the skeletons on page 236 • They are adapted to different ways of life • Trees vs. us; herbivores vs omnivores

  19. Page 237: Analyze a human and a chimp • Answer questions – work together if wish

  20. Page 238: Skull analysis • Answer questions regarding facial features (page 238)

  21. Molecular Evidence • Almost all living organisms use the same basic biochemical molecules • DNA, ATP, Proteins (same amino acids)

  22. Protein differences • Protein Clock Hypothesis • Number of amino acid changes between organisms is proportional to the length of time since the two organisms began evolving separately from a common ancestor.

  23. Protein Similarities • Immune system makes antibodies (proteins) • React with foreign proteins – Antigens • Antigen-antibody reactions are specific

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