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Evolution Evidence and Theory

Evolution Evidence and Theory. Chapter 15 Lab Biology. Evolution. A genetic change within a population over time! Population- interbreeding single-species group. Fossils. Fossil - trace of a long-dead organism.

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Evolution Evidence and Theory

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  1. EvolutionEvidence and Theory Chapter 15 Lab Biology

  2. Evolution • A genetic change within a population over time! • Population- interbreeding single-species group

  3. Fossils • Fossil - trace of a long-dead organism. • Sedimentary rock - formed by dust, sand, or mud deposited by wind or water over dead organism • Formed by hard body parts of an organism—shell, bones, teeth, or woody stems • Hard minerals replace the tissue of the organism leaving rocklike structures

  4. Sedimentary Rock

  5. Continue Fossils 2. mold – imprint in rock in the shape of an organsim - limestone 3. cast – forms when molds are filled with hard minerals

  6. Limestone • Limestone – most abundant , non-classic sedimentary rocks. • Limestone is produced from the mineral calcite (calcium carbonate) and sediment. • Chalk is another type of limestone that is made up of very small single-celled organisms.

  7. Cast • !

  8. Robert Hooke 1635-1703 • He concluded that fossils are remains of plants and animals • He mostly studied “petrified wood” with the aid of the microscope • He hypothesized that living organisms had somehow been turned to rock

  9. Petrified WoodWood that has turned to stone!

  10. Distribution of Fossils • Nicolaus Steno (1638-1686) • “law of superpositon” – states that the top layers of stratum contain the youngest fossils while the lower ones are older • This technique helps scientists to determine the “relative age” of a fossil • “absolute age”- age in years determined by radiological evidence

  11. Succession of Forms • Mass extinctions – brief periods during which large numbers of species disappears. • Some of these life forms were unlike any organisms alive today • Probably resulted from drastic changes in the environment, volcanic activity or collisions with asteroids (may have blocked sunlight for long periods of time and decreased temp.)

  12. Biogeography • Biogeography – is the study of the geographical distribution of fossils and of living organisms. • A comparison of fossil types with types of living organisms in the same geographic area • shows that new organisms arise in areas where similar forms already lived. • Ex: armadillos in North & South America where glyptodonts lived in the past.

  13. Armadillos

  14. Glyptodonts

  15. ScaphognathuscrassirostrisLab Fossil

  16. Theories of Evolution • I. Lamarck’s Explanation: • He hypothesized that acquired traits were passed on to offspring. • Proposed that similar species descended from a common ancestor (fossil records)

  17. Acquired Trait • It’s not determined by genes! • Occurs during an organism’s lifetime • result of the organism’s experience or behavior. • Ex: 1. Muscles on a body builder • 2. Giraffe’s necks did not get longer by trying harder and harder to reach tall trees- Genetic

  18. Beginning of Modern Evolutionary Theory • II. Charles Darwin (1809-1882) & Alfred Wallace (1823-1913) • Darwin & Wallace announced their hypotheses at the same time • Darwin’s name became more associated with evolution The Origin of Species published

  19. Darwin’s Voyage on the Beagle • Sailed in 1831 for five years • Collected specimens and kept careful records of his observations • Sailed to South America (Galapagos Islands) and the South Pacific

  20. Voyage of the Beagle

  21. Darwin’s Findings • Collected 13 similar but separate species of finches. • Each finch species had a distinctive bill for specialized food source. • Implied that the finches shared a recent common ancestor

  22. Darwin’s Finches

  23. Darwin’s Findings

  24. Darwin’s Theories • TWO THEORIES; • 1. DESCENT WITH MODIFICATION – The newer forms appearing in the fossil record are actually the modified descendants of older species • Organisms similar to each other- common ancestor • Organisms that are dissimilar -share a more remote ancestor

  25. Continue… • 2. MODIFICATION BY NATURAL SELECTION – states HOW evolution occurs. • Organisms best suited to their environment reproduces more successfully than other organisms

  26. Adaptation- Adaptive advantage • A population of organisms adapt to their environment • # of genes for favorable traits increases • Fitness- a single genetic organism’s contribution to the next generation’s survival • A well adapted organism will reproduce successfully and have a high fitness

  27. High Fitness? Low Fitness?

  28. High Fitness? Low Fitness?

  29. High Fitness? Low Fitness?

  30. High Fitness? Low Fitness?

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