Unit 11 evolution of populations

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Unit 11 evolution of populations

  1. 1. KEY CONCEPT New technology is furthering our understanding of evolution.<br />
  2. 2. Fossils provide a record of evolution. <br />Paleontology is the study of fossils or extinct organisms.<br />
  3. 3. Paleontology provides evidence to support evolution.<br />
  4. 4. Molecular and genetic evidence support fossil and anatomical evidence. <br />Two closely-related organisms will have similar DNA sequences. What would you expect to find the differences code for?<br />
  5. 5. Pseudogenes are sequences providing evidence of evolution.<br /><ul><li>no longer function
  6. 6. carried along with functional DNA
  7. 7. can be clues to a common ancestor</li></li></ul><li>Hox genes indicate a very distant common ancestor.<br /><ul><li>control the development of specific structures
  8. 8. found in many organisms
  9. 9. Protein comparisons, or molecular fingerprinting reveals similarities among cell types of different organisms.</li></li></ul><li>Evolution unites all fields of biology. <br /><ul><li>Scientists from many fields contribute to the understanding of evolution.
  10. 10. The basic principles of evolution are used in many scientific fields. Some for good purposes and some for less ethical – give an example of each.</li></li></ul><li>KEY CONCEPT A population shares a common gene pool.<br />
  11. 11. Remember me?<br />Genotypic<br />Phenotypic<br />
  12. 12. Genetic variation in a population increases the chance that some individuals will survive.<br />Genetic variation leads to phenotypic variation. Why?<br />Phenotypic variation is necessary for natural selection. Why?<br />Genetic variation is stored in a population’s gene pool.<br />made up of all alleles in a population<br />allele combinations form when organisms have offspring – How?<br />
  13. 13. Allele frequencies measure genetic variation.<br /><ul><li>measures how common an allele is in population
  14. 14. can be calculated for each allele in gene pool</li></li></ul><li>Genetic variation comes from several sources.<br />Mutation is a random change in the DNA of a gene.<br /><ul><li> can form new allele
  15. 15. can be passed on to offspring if in reproductive cells – why not from body cells?
  16. 16. Recombination forms new combinations of alleles.
  17. 17. usually occurs during meiosis
  18. 18. parents’ alleles arranged in new ways in gametes</li></li></ul><li>Genetic variation comes from several sources.<br />Hybridization is the crossing of two different species.<br />occurs when individuals can’t find mate of own species<br />topic of current scientific research<br />
  19. 19. KEY CONCEPT Populations, not individuals, evolve.<br />
  20. 20. Natural selection acts on distributions of traits. <br />A normal distribution graphs as a bell-shaped curve.<br /><ul><li> highest frequency near mean value
  21. 21. frequencies decrease toward each extreme value
  22. 22. Traits not undergoing natural selection have a normal distribution.
  23. 23. Give an example of a trait that could have a normal distribution.</li></li></ul><li>Natural selection can change the distribution of a trait in one of three ways. <br />Microevolution is evolution within a population.<br />observable change in the allele frequencies <br />can result from natural selection<br />
  24. 24. Natural selection can take one of three paths. <br /><ul><li>Directional selection favors phenotypes at one extreme. What’s happening in this graph?</li></li></ul><li>Natural selection can take one of three paths. <br /><ul><li>Stabilizing selection favors the intermediate phenotype.
  25. 25. What’s happening in this graph?</li></li></ul><li>Natural selection can take one of three paths. <br /><ul><li>Disruptive selection favors both extreme phenotypes.
  26. 26. What is happening in this graph?</li></li></ul><li>Where does genetic variation come from? <br />A. Mutation only <br />B. Both mutation and recombination <br />C. Recombination only <br />D. Mitosis only <br />
  27. 27. Where does genetic variation come from? <br />A. Mutation only <br />B. Both mutation and recombination <br />C. Recombination only <br />D. Mitosis only <br />Correct Answer = B<br />Where is the most common phenotype found in a normal distribution? <br />A. In the middle range <br />B. At the low range <br />C. At the high range <br />D. Equally across the distribution range<br />
  28. 28. Where does genetic variation come from? <br />A. Mutation only <br />B. Both mutation and recombination <br />C. Recombination only <br />D. Mitosis only <br />Correct Answer = B<br />Where is the most common phenotype found in a normal distribution? <br />A. In the middle range <br />B. At the low range <br />C. At the high range <br />D. Equally across the distribution range<br />Correct Answer = A<br />
  29. 29. Review<br />Paleontology is the study of fossils – it provides evidence for evolution in a predictable fashion<br />Genetics gives evidence of evolution – similar gene sequences are found in related organisms<br />Pseudogenes are segments of DNA that no longer function but give clues to evolutionary history<br />Evolution unites the study of Biology in a similar way as Einstein’s famous E=mc2 unites Physics.<br />Genetic variation increases the chances that some individuals will survive.<br />Allele frequencies measure the variation in a species<br />
  30. 30. Review<br />Genetic variation comes from several sources<br />Mutations<br />Recombination<br />Hybridization<br />Populations evolve – not individuals<br />Natural Selection can take one of three paths<br />Directional – moving towards one extreme<br /> Stabilizing – moving towards the mean value<br />Disruptive – moving towards both extremes<br />

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