Evolution

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Evolution

  1. 1. Evolution
  2. 2. What is Evolution? <ul><li>Evolution - how modern day organisms have changed from ancient organisms. </li></ul><ul><li> - gradual “change over time” </li></ul>
  3. 3. Charles Darwin <ul><li>Collected data and observations to create hypothesis about evolution. </li></ul><ul><li>Published On the Origin of Species containing his theory of evolution . </li></ul>
  4. 4. Darwin’s Observations <ul><li>He visited many continents while serving on the ship H.M.S Beagle. </li></ul><ul><li>He noticed a great diversity (variety) in organisms (species) on these different continents . </li></ul><ul><li>Australia – Kangaroos </li></ul><ul><li>Galapagos – Giant Tortoises and Finches </li></ul>
  5. 5. Species <ul><li>Species – a group of organisms that can reproduce and create offspring that can reproduce. </li></ul>
  6. 6. Who Survives? <ul><li>Natural Selection – those individuals who have favorable variations (from their genes) are able to survive and reproduce successfully. </li></ul>
  7. 7. Conditions for Natural Selection <ul><li>Overproduction – every species produces more individuals than will survive. </li></ul><ul><li>Ex: insects, fish, dandelions </li></ul>
  8. 8. <ul><li>2. Struggle for Survival – individuals within a species will compete for resources. </li></ul><ul><li>- Ex: environmental conditions: food, space, water, etc. </li></ul>
  9. 9. <ul><li>3. Adaptation (adaptive value) – any genetic trait that helps an organism survive, compete, and reproduce better than others. </li></ul><ul><li>- Ex: Grasshoppers with longer legs </li></ul><ul><li> Lions with sharper teeth </li></ul>
  10. 10. Where Do Variations Come From? <ul><li>Genetic variations can only be passed on if they occur in gamete cells . </li></ul><ul><li>Sources of variation: </li></ul><ul><li>a. Mutation – change in DNA bases. </li></ul><ul><li>- Some are “good” and can be passed on . </li></ul><ul><li>b. Sexual Reproduction – crossing over of chromosomes and sexual recombination (fertilization) increases variety in offspring. </li></ul>
  11. 11. <ul><li>Mutations occur at random – “good” ones will become popular and passed on. </li></ul>
  12. 12. <ul><li>Survival of the Fittest – individuals who have certain variations will be able to survive if environment changes. </li></ul><ul><li>- Ex: Disease and resistance/immunity </li></ul>
  13. 13. <ul><li>5. Speciation – those individuals that survived to reproduce, may develop into a new species. </li></ul><ul><li>How does it happen? </li></ul><ul><li>Reproductive isolation – a population may become separated by a geographical barrier. </li></ul><ul><li>- Ex: River, mountain range, earthquake, ocean </li></ul>
  14. 14. <ul><li>Many new species of finches develop from isolation. </li></ul><ul><li>Differences in beak sizes/shapes result from different environments (food sources). </li></ul>
  15. 15. Examples of Natural Selection <ul><li>Peppered Moth Evolution </li></ul><ul><li>Change in moth color from white to black due to change in their environment from white to black. </li></ul><ul><li>Black moth color = “favorable” mutation </li></ul>
  16. 16. <ul><li>Antibiotic Resistance </li></ul><ul><li>Antibiotics – kill bacteria with diseases. </li></ul><ul><li>Through natural selection, some bacteria mutate and become resistant (not affected) to antibiotics . </li></ul><ul><li>These resistant bacteria multiply (asexually) and soon become the only bacteria around. </li></ul><ul><li>New antibiotics must now be made. </li></ul><ul><li>http://www.pbs.org/wgbh/evolution/library/10/4/l_104_03.html </li></ul>
  17. 17. Red Bacteria have mutation for resistance After Treated with Antibiotic Only Red Bacteria survive and pass on good mutation
  18. 18. Evidence of Evolution <ul><li>Similarities in DNA and Proteins </li></ul><ul><li>Proteins from 2 different species may have similar amino acid sequences. </li></ul><ul><li>- Ex: Humans and Chimpanzees share same protein for blood which differs by only 1-2 amino acids. </li></ul>
  19. 19. <ul><li>2. Similarities in Embryo Development </li></ul><ul><li>Early stages of embryos in many animals is very similar. </li></ul><ul><li>- Differentiation happens the same way in many organisms. </li></ul><ul><li>- Suggests we come from a common ancestor . </li></ul>
  20. 20. <ul><li>3. Homologous Body Structures </li></ul><ul><li>Similarities in forelimb bones of different animal species: wing of a bat, flipper of a whale, arm of a human. </li></ul><ul><li>- Bones are attached in similar places  all came from a common ancestor . </li></ul>
  21. 21. <ul><li>Vestigial structures – organs that serve no function in an organism. </li></ul><ul><li>- may have been useful in the past. </li></ul><ul><li>- Ex: human appendix, leg bones in whale </li></ul>
  22. 22. <ul><li>4. Fossil Record – fossils from different layers of the earth show species have changed over time. </li></ul><ul><li>- The earth is approximately 4.7 billion years old . </li></ul>
  23. 23. Origin of Life <ul><li>First organisms were single-celled (bacteria). </li></ul><ul><li>As time went on, more complex multicellular organisms developed. </li></ul><ul><li>Now, the most complex multicellular organisms (humans) have evolved. </li></ul>
  24. 24. Extinction <ul><li>Extinction - Disappearance of species from the earth. </li></ul><ul><li>- Species cannot adapt to changing environment . </li></ul><ul><li>- Natural disaster (meteor) </li></ul>
  25. 25. - Bottom layers= oldest (simplest) - Top layers = most recent (more complex)
  26. 26. Phylogenetic (Family) Trees <ul><li>Family Tree - Simple diagram used to show relationships and common ancestors amongst species. </li></ul>
  27. 27. A B C D F E G Past Present E is a common ancestor to both B and C! Family Tree
  28. 29. Punctuated Equilibrium <ul><li>Punctuated Equilibrium – long, stable periods of equilibrium interrupted by rapid change (due to mutations). </li></ul><ul><li>- Different speeds of evolution for different species. </li></ul>

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