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Biol161 07 Bw


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Biol161 07 Bw

  1. 1. Ocean County College BIOL 161 Lectures Genetics ... The grand synthesis … BIOL161_07
  2. 2. An incomplete history <ul><li>Domestication of plants and animals
  3. 3. Frances Galton and Karl Pearson </li><ul><li>late 19th and early 20th centuries
  4. 4. human variation in morphometry and behavior </li></ul><li>Charles Darwin (1861)
  5. 5. What happened to Mendel? *** February 8, 1865 *** </li><ul><li>Rediscovery by Tschermak (Austria), Correns (Germany) and DeVries (Holland) (1903, 1904) </li></ul></ul>
  6. 6. Qualitative Inheritance P 1 P 2 F 2 Number Frequency
  7. 7. Comb types in chickens <ul><li>Single
  8. 8. Rose
  9. 9. Pea
  10. 10. Cushion </li></ul><ul><li>Buttercup (V-Shaped) </li><ul><li>Duplex </li></ul><li>Strawberry
  11. 11. V-shaped
  12. 12. Silkie </li></ul>There are eight basic comb-types in chickens. In addition, there are several modifying genes (like ‘self-dubbing’, ‘spike’, making comb-typing an adventure!
  13. 13. Comb types – what they really look like! <ul><li>Rose
  14. 14. Pea </li></ul><ul><li>Single
  15. 15. Walnut </li></ul>
  16. 16. Two genes; One Phenotype (P) <ul><li>Single, pea, rose, walnut </li><ul><li>Comb-type in chickens </li></ul></ul>
  17. 17. Two genes; one phenotype (G) <ul><li>Single, pea, rose, walnut </li><ul><li>Comb-type in chickens </li></ul></ul>
  18. 18. The Pea-Comb Phenotype <ul><li>These are individuals carrying the pea-comb allele
  19. 19. All in the genetic background of a cross of Chinese Hua-Tung and Russian Orlov breeds
  20. 20. Note male/female differences! </li></ul>From Wright et al., PLoS Genet. 2009 June; 5(6): e1000512.
  21. 21. The resolution <ul><li>Identification of the pea-comb mutation
  22. 22. Note the duplication in the repeated sequence
  23. 23. Variation in copy number of the 1 st intron in SOX5 causes the phenotype!!! </li></ul>
  24. 24. Biological Complexity Revealed Gerstein M B et al. Genome Res. 2007;17:669-681 ©2007 by Cold Spring Harbor Laboratory Press
  25. 25. Quantitative Inheritance P 1 P 2 F 2 Frequency Height
  26. 26. Mendel vs. the Biometricians <ul><li>Bateson and DeVries </li><ul><li>traits having continuous variation could only be produced by environmental variation and NOT inherited </li></ul><li>Only large discontinuous differences or variation could be caused by ‘genes’.
  27. 27. These were considered to be measurable, or metrical, traits. </li></ul>
  28. 28. The Resolution <ul><li>Johannsen (1909) </li><ul><li>Seed weight in beans was influenced by both genes and environment </li></ul><li>Nilsson-Ehle (1910-1914) </li><ul><li>Multiple genes control grain color in wheat </li></ul><li>R. A. Fisher (1918) </li><ul><li>The additive model was proposed! </li></ul></ul>
  29. 29. Phenotypic Distribution of a Quantitative Trait
  30. 30. The Stars <ul><li>Sir Kenneth Mather </li><ul><li>1949 -- Biometrical Genetics </li></ul><li>The players </li><ul><li>R. A. Fisher & J. B. S. Haldane (UK)
  31. 31. Sewell Wright & Jay Lush (US) </li></ul><li>The places </li><ul><li>Iowa State & Edinburgh </li><ul><li>hogs, poultry, cattle, sheep </li></ul><li>NC State & Birmingham </li><ul><li>maize and tobacco (NC), inbred plants (B) </li></ul></ul></ul>
  32. 32. The Additive Model of Inheritance <ul><li>P = G + E </li><ul><li>Phenotype, Genotype, Environment </li></ul><li>What about G*E ? </li><ul><li>Genotype by Environment Interaction </li></ul><li>and, How about G ~ E ? </li><ul><li>Genotype-Environment Correlation </li></ul><li>Simplifying assumptions </li></ul>
  33. 33. The world and plants
  34. 34. The 7 Neolithic Founder Crops
  35. 35. Wait a minute … What’s domestication? <ul><li>Economic Use such as meat, fur, eggs, milk, labor companionship!! </li></ul><ul><li>The breeding, care and feeding of the animal are under the continuous control of man </li></ul><ul><li>Any situation where artificial selection has replaced, in part, natural selection </li></ul>
  36. 38. The world, plants and animals
  37. 39. Trait changes associated with domestication <ul><li>SIZE: </li><ul><li>Early domestic animals were smaller than their wild counterparts. Now they are larger, due to artificial selection. </li></ul><li>COLOR: </li><ul><li>Many more colors in domestic varieties than observed in the wild. </li></ul><li>SKULL </li><ul><li>Facial features shortened relative to cranial size. This is especially evident in swine and sheep. The teeth get smaller and horns decrease in size. </li></ul><li>SKELETON: </li><ul><li>Domestic cattle have weak muscle ridges and poorly defined facets of the joints. In domestic pigs, the epiphyses of the limb bones do not fuse with the diaphyses until long after maturity. </li></ul></ul>