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Last Time…. Biston betularia. Distribution Map Biston betularia f. typica. 1840 Distribution Map. 1600. 1900. 2000. 1800. 1700. Discovery Biston betularia f. carbonaria. 1848 - Manchester, UK. 1600. 1900. 2000. 1800. 1700. James W. Tutt. (1858-1911). Manchester in 1843.

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Last Time…

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  1. Last Time…

  2. Biston betularia

  3. Distribution Map Biston betularia f. typica 1840 Distribution Map 1600 1900 2000 1800 1700

  4. DiscoveryBiston betularia f. carbonaria 1848 - Manchester, UK 1600 1900 2000 1800 1700

  5. James W. Tutt (1858-1911) Manchester in 1843 1600 1900 2000 1800 1700

  6. 1950 Centers of pollution Frequency of dark form Glasgow Manchester London 1600 1900 2000 1800 1700

  7. Mystery PhenomenonPart 2

  8. Unpolluted vs. Polluted Forest

  9. Unpolluted Woods & Moths

  10. Polluted Woods & Moths

  11. Three Theories 1. Physiological Response to Changed Environment 2. Natural Selection 3. Mutation

  12. Three Theories 1’ . Lamarck’s Theory of Acquired Inheritance 2’. Darwin’s Theory of Natural Selection 3’. De Vries’ Mutation Theory

  13. Lamarckian Inheritance • All creatures have a natural tendency to become more complex. • Changes in behavior can result in morphological changes inherited by offspring Jean Baptiste Lamarck (1744-1829)

  14. Lamarckian InheritanceApplied to the Mystery Phenomenon • This trend is the result of the moths adapting to environmental conditions that have led to a general darkening of their resting sites, such as pollution and increased humidity. • Individuals adapt to local circumstances and these changes are passed to their offspring. Nicholas Cooke (1818-1886) 1600 1900 2000 1800 1700

  15. Natural Selection • There are small heritable variations within populations. • Some variations give their possessors a better chance at surviving and reproducing. • Over time the favored variation will become more common. Charles Darwin (1809-1882)

  16. Natural Selection& the Mystery Phenomenon • Increase of the dark form is due to crypsis or the protective advantage of dark color in soot- darkened environments. J.W. Tutt 1858-1911) 1600 1900 2000 1800 1700

  17. Natural Selection& the Mystery Phenomenon • The spread of the dark form is due to its physiological superiority over the pale form. • The spread is limited to areas darkened by pollution owing to the handicap of dark coloration in unpolluted environments. E.B. Ford (1901-1988) 1600 1900 2000 1800 1700

  18. Mutation Theory • Speciation is the result of large discontinuous changes caused by mutations that produce offspring radically different than their parents. Hugo De Vries (1848-1935)

  19. Mutation Theory&the Mystery Phenomenon • Lead salts in the pollutants covering the foliage of trees have mutagenic properties. • Exposure to these salts has led to this mutation. Heslop Harrison (1881-1967) 1600 1900 2000 1800 1700

  20. To Sum it Up…

  21. Cooke’s Theory Increasing Pollution

  22. Tutt & Ford’s Theory Increasing Pollution

  23. Heslop Harrison’s Theory Increasing Pollution

  24. What is a theory?

  25. How do scientists choose between competing theories?

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