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Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
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Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
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Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
Theoryofevolution 110815170612-phpapp01
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Theoryofevolution 110815170612-phpapp01

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Theory of evolution

Theory of evolution

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  • 1. Theory of Evolution By Nonhlanhla Nkosi
  • 2. Definiti on • Evolution is the slow , gradual change in a population of organisms over time 2
  • 3. Isn’t evolution “just a theory”? In every day usage “theory” often refers to a hunch or a speculation. When people say, “I have a theory about what happened,” they are often drawing a conclusion based on fragmentary or inconclusive evidence. The formal scientific definition of “theory” is quite different from the every day meaning. It refers to a comprehensive explanation of some aspect of nature that is supported by a vast body of evidence. http://evolution.berkeley.edu/evosite/evohome.htm
  • 4. Evolution Pre-Darwin Beliefs • Earth was only a few thousand years old. • We now know it is billions of years old. • Neither the planet nor the species that inhabited it had changed since the beginning of time. • We now know the planet has changed and, through fossils, discovered organisms have changed, as well.
  • 5. THE THEORY OF EVOLUTION • CHARLES DARWIN • EVIDENCE FOR EVOLUTION • MECHANISMS FOR EVOLUTION • NATURAL SELECTION • SPECIATION http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 6. Charles Darwin the Naturalist 6
  • 7. THE THEORY OF EVOLUTION • CHARLES DARWIN • EVIDENCE FOR EVOLUTION • MECHANISMS FOR EVOLUTION • NATURAL SELECTION • SPECIATION Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. http://evolution.berkeley.edu/evolibrary/home.php
  • 8. Voyage of the Beagle Charles Darwin • Born Feb. 12, 1809 • Joined Crew of HMS Beagle, 1831 • Naturalist • 5 Year Voyage around world • Avid Collector of Flora & Fauna • Astounded By Variety of Life 8
  • 9. Darwin Left England in 1831 Darwin returned 5 years later in 1836 9
  • 10. EVIDENCE OF EVOLUTION • STRUCTURAL ADAPTATIONS • MIMICRY – the insect looks like the leaf • CAMOUFLAGE – the chameleon can change color to match its surroundings http://evolution.berkeley.edu/evolibrary/home.php http://science.howstuffworks.com/animal-camouflage2.htm Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 11. EVIDENCE OF EVOLUTION • STRUCTURAL ADAPTATIONS • MIMICRY • CAMOUFLAGE • MILLIONS OF YEARS • PHYSIOLOGICAL ADAPTATIONS • CHANGE IN A METABOLIC PROCESS • WHAT DO YOU HEAR ABOUT IN THE NEWS ABOUT SOME BACTERIA? Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 12. The Galapagos Islands • Small Group of Islands 1000 km West of South America • Very Different Climates • Animals On Islands Unique • Tortoises • Iguanas • Finches 12
  • 13. The Galapagos Islands • Volcanic islands off the coast of South America • Island species varied from mainland species & from island-to-island species • Each island had long or short neck tortoises 13
  • 14. 14
  • 15. The Galapagos Islands • Finches on the islands resembled a mainland finch • More types of finches appeared on the islands where the available food was different (seeds, nuts, berries, insects…) • Finches had different types of beaks adapted to their type of food gathering 15
  • 16. 16
  • 17. Darwin’s Observations • Patterns of Diversity Patterns of Diversity were shown • Unique Adaptations in organisms • Species Not Evenly Distributed • Australia, Kangaroos, but No Rabbits • S. America, Llamas 17
  • 18. Darwin’s Observations • Both Living Organisms & Fossils collected • Fossils included: •Trilobites •Giant Ground Sloth of South America This species NO longer existed. What had happened to them? 18
  • 19. Evidence for Evolution – The Fossil Record 19
  • 20. Darwin’s Observations • Left unchecked, the number of organisms of each species will increase exponentially, generation to generation • In nature, populations tend to remain stable in size • Environmental resources are limited 20
  • 21. Darwin’s Observations • Individuals of a population vary extensively in their characteristics with no two individuals being exactly alike. • Much of this variation between individuals is inheritable. 21
  • 22. Darwin’s Conclusion • Production of more individuals than can be supported by the environment leads to a struggle for existence among individuals • Only a fraction of offspring survive each generation • Survival of the Fittest 22
  • 23. Darwin’s Conclusion • Individuals who inherit characteristics most fit for their environment are likely to leave more offspring than less fit individuals • Called Natural Selection 23
  • 24. OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY • HOMOLOGOUS STRUCTURES – structures that are similar because they are inherited from a common ancestor http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 25. OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY • HOMOLOGOUS STRUCTURES • ANALOGOUS STRUCTURES – structures that are similar because they serve the same function but do not have a common ancestor. http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 26. OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY • HOMOLOGOUS STRUCTURES • ANALOGOUS STRUCTURES • VESTIGIAL STRUCTURE – a feature inherited from an ancestor that is now less elaborate and functional, usually formed when a population experiences a different environment http://evolution.berkeley.edu/evolibrary/home.php WHAT IS ANOTHER EXAMPLE OF VESTIGIAL STRUCTURES? These fish live in the dark and therefore do not need functional eyes. Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 27. OTHER EVIDENCE OF EVOLUTION • FOSSILS • ANATOMY • HOMOLOGOUS STRUCTURES • ANALOGOUS STRUCTURES • VESTIGIAL STRUCTURE • EMBRYOS Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. http://evolution.berkeley.edu/evolibrary/home.php
  • 28. Similarities In Early Development • Embryonic Structures Of Different Species Show Significant Similarities • Embryo – early stages of vertebrate development 28
  • 29. Human Fetus – 5 weeks 29
  • 30. Chicken Turtle Rat 30
  • 31. MECHANISMS FOR EVOLUTION • DO POPULATIONS OR INDIVIDUALS EVOLVE? • WHAT IS A GENE POOL? • HOW CAN THE GENE POOL CHANGE? • MUTATION • GENETIC DRIFT • GENE FLOW • WOULD THESE THINGS EFFECT A LARGE POPULATION OR A SMALL POPULATION MORE? Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 32. Any change in an organism’s DNA When some organisms RANDOMLY survive longer than others and pass on their genes. The movement of genes from one population to another through migration of individuals. ALL IMAGES: http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 33. THE THEORY OF EVOLUTION • CHARLES DARWIN • EVIDENCE FOR EVOLUTION • MECHANISMS FOR EVOLUTION • NATURAL SELECTION • SPECIATION http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 34. WHAT IS NATURAL SELECTION? Variation in some traits (color of beetles) Green beetles tend to get eaten and do not survive long enough to reproduce The surviving brown beetles have brown offspring. Eventually all the green beetles get eaten, leaving only brown beetles. http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 35. Darwin’s Theory of Evolution Organisms Change Over Time 35
  • 36. Common Descent with Modification • Darwin proposed that organisms descended from common ancestors • Idea that organisms change with time, diverging from a common form • Caused evolution of new species 36
  • 37. Natural Selection • The Struggle for Existence (compete for food, mates, space, water, etc.) • Survival of the Fittest (strongest able to survive and reproduce) • Descent with Modification (new species arise from common ancestor replacing less fit species) 37
  • 38. Natural selection • Fitness • Ability of an Individual To Survive & Reproduce • Adaptation • Inherited Characteristic That Increases an Organisms Chance for Survival 38
  • 39. Natural selection • Adaptations Can Be: • Physical • Speed, Camouflage, Claws, Quills, etc. • Behavioral • Solitary, Herds, Packs, Activity, etc. 39
  • 40. Survival of the Fittest • Fitness Is Central To The Process Of Evolution • Individuals With Low Fitness • Die • Produce Few Offspring Survival of the Fittest AKA Natural Selection 40
  • 41. Natural selection Key Concept Over Time, Natural Selection Results In Changes In The Inherited Characteristics Of A Population. These Changes Increase A Species Fitness In Its Environment 41
  • 42. IMPORTANT TO REMEMBER ! •POPULATIONS evolve NOT INDIVIDUALS. •NATURAL SELECTION only works on heritable traits. •A trait that is favorable in one environment may be useless or detrimental in another.
  • 43. THE THEORY OF EVOLUTION • CHARLES DARWIN • EVIDENCE FOR EVOLUTION • MECHANISMS FOR EVOLUTION • NATURAL SELECTION • SPECIATION http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 44. WHAT IS SPECIATION? • GEOGRAPHIC ISOLATION A barrier, either physical, like a river changing course, or nonphysical, causes the population to become separated. http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 45. WHAT IS SPECIATION? • GEOGRAPHIC ISOLATION • REPRODUCTIVE ISOLATION • for example, what might occur between fruit flies raised on different types of food? • when allowed to interact, some would only mate with the same food preference as itself Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College. http://evolution.berkeley.edu/evolibrary/home.php
  • 46. BOTH LIVE IN FOREST ECOSYSTEMS Adapted to similar environments, but evolved independently from different ancestors. SUGAR GLIDER in Australia is a marsupial more closely related to Kangaroos than North American FLYING SQUIRRELS because its ancestors were marsupials.
  • 47. WHAT IS SPECIATION? • GEOGRAPHIC ISOLATION • REPRODUCTIVE ISOLATION • PACE OF EVOLUTION: Gradualism – slow steady change over a long time Punctuated equilibrium – a large amount of change in a short time due to a specific event. Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 48. WHAT IS SPECIATION? • GEOGRAPHIC ISOLATION • REPRODUCTIVE ISOLATION • GRADUALISM • PUNCTUATED EQUILIBRIUM • DIVERGENT EVOLUTION – two species that are now dissimilar but can be traced back to the same ancestor • ADAPTIVE RADIATION – adaptations to survive in new environmental conditions • CONVERGENT EVOLUTION – species having similar features in spite of not having the same ancestor Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 49. ADAPTIVE RADIATION – AN EXAMPLE OF DIVERGENT EVOLUTION http://www.vanderbilt.edu/AnS/english/Clayton/Galapago_finches.gif http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 50. CONVERGENT EVOLUTION –EXAMPLE http://evolution.berkeley.edu/evolibrary/home.php Life Sciences-HHMI Outreach. Copyright 2006 President and Fellows of Harvard College.
  • 51. Evolutionary Timeline 51
  • 52. Lamarck’s Theory of Evolution • Jean-Baptiste Lamarck, 1809 • One Of First Scientists To Understand That Change Occurs Over Time • Stated that Changes Are Adaptations To Environment acquired in an organism’s lifetime • Said acquired changes were passed to offspring 52
  • 53. Lamarck’s Theory of Evolution • Idea called Law of Use and Disuse • If a body part were used, it got stronger • If body part NOT used, it deteriorated 53
  • 54. Lamarck’s Theory of Evolution • Inheritance of Acquired Characteristics • Proposed That By Selective Use Or Disuse Of Organs, Organisms Acquired Or Lost Certain Traits During Their Lifetime • These Traits Could Then Be Passed On To Their Offspring • Over Time This Led To New Species 54
  • 55. Lamarck’s Theory of Evolution • Use & Disuse - Organisms Could Change The Size Or Shape Of Organs By Using Them Or Not Using Them • Blacksmiths & Their Sons (muscular arms) • Giraffe’s Necks Longer from stretching) 55
  • 56. 56
  • 57. INHERITANCE OF ACQUIRED CHARACTERISTICS The male fiddler crab uses its front claw to attract mates and ward off predators. “USE or DISUSE” = Use it or lose it Through repeated use, the front claw becomes larger. The fiddler passes on this acquired characteristic to its offspring
  • 58. http://www.geocities.com/arnold_schwarzenegger_pictures/ What’s wrong with Lamarck’s hypothesis? Lamarck didn’t know about genes and how traits are inherited. Acquired traits are not passed on to offspring Or are they? . . . New field of EPIGENETICS is exploring this
  • 59. Lamarck’s Theory of Evolution • Inheritance Of Acquired Traits • Traits Acquired During Ones Lifetime Would Be Passed To Offspring 59 59 Clipped ears of dogs could be passed to offspring!
  • 60. Publication of “On The Origin of Species” • Darwin Knew That His Theory Would Be Extremely Controversial And Would Be Attacked • His Theory Challenged Established Religious & Scientific Beliefs, Particularly About The Creation Of Man 60
  • 61. Publication of “On The Origin of Species” • He Refused To Publish Until He Received An Essay From Alfred Wallace • Fellow Naturalist • Independently Developed The Same Theory • After 25 Years, Someone Else Had Come To The Same Conclusions From Their Observations Of Nature 61
  • 62. Wallace’s Contribution • Alfred Russel Wallace Independently came to same Conclusion as Darwin that species changed over time because of their struggle for existence • When Darwin read Wallace’s essay, he knew he had to publish his findings 62
  • 63. Publication of “On The Origin of Species” • Darwin Presented Wallace’s Essay & Some Of His Work At A Scientific Conference of the Linnaean Society in July of 1858 • Then He Started On his book “Origin of Species” • It Took Darwin 18 Months To Complete The Book 63
  • 64. Natural Variation and Artificial Selection • Abandoned The Idea That Species Were Perfect & Unchanging • Observed Significant Variation in All Species Observed • Observed Farmers Use Variation To Improve Crops & Livestock • Called Selective Breeding 64
  • 65. Natural Variation and Artificial Selection • Natural Variation • Differences Among Individuals Of A Species • Artificial Selection • Selective Breeding To Enhance Desired Traits Among Stock or Crops 65
  • 66. Natural Variation and Artificial Selection Key Concept: In Artificial Selection, Nature Provided The Variation Among Different Organisms, And Humans Selected Those Variations That They Found Useful 66
  • 67. 67
  • 68. Slide by Kim Foglia@ http://www.explorebiology.com/
  • 69. Can see Natural selection happen EX: Changes in disease-causing microbes that produce new organisms and new diseases. Bird flu _______ HIV ___ http://www.hhmi.org/askascientist/images/hiv.gif Antibiotic-resistant tuberculosis __________________________ Why does evolution matter now? http://www.hipusa.com/eTools/webmd/A-Z_Encyclopedia/tuberculosis.jpg
  • 70. Mutation, Evolution, and Natural Selection DNA is found in the nucleus of the cell • Http://www.youtube.com/watch?v=ZK6YP1Smbxk
  • 71. Mutation A mutation is a change in gene sequence. • A mutation is a change in gene sequence. • There are many different types of mutations and causes for them. • Some mutations are harmful, while others can be beneficial.
  • 72. Harmf ul Beneficial
  • 73. How does mutations work? • DNA is very accurate when making copies of itself, however, sometimes it makes a mistake. • Here’s a DNA sequence • AGCCCTTATAGGCTC • What are the corresponding base pairs? • TCGGGAATATCCGAG • Now when it’s being copied it replaces the T with a U. Rewrite the your answer with U’s instead of T’s. • UCGGGAAUAUCCGAG • What amino acids will this be coded for? • Serine, Glycine, Isoleucine, Serine, Glutamic Acid
  • 74. The Mutation • Here’s our original DNA sequence • AGCCCTTATAGGCTC • ATCCCTTATAGGCTC we replaced the G with a T • Now what are the corresponding base pairs? • TAGGGAATATCCGAG • Now when it’s being copied it replaces the T with a U. Rewrite the your answer with U’s instead of T’s. • UAGGGAAUAUCCGAG • What amino acids will this be coded for? • Stop, Glycine, Isoleucine, Serine, Glutamic Acid • You can see how replacing 1 base will change everything!
  • 75. References • This is a mash up of 5 different sources which are: • Allen, A. (2011). Theory of Evolution. http://www.slideshare.net/MsAllenBio/theory-of-evolution-8858675 • Zolli. (2012). Evolution and Natural selection- How species change over time . http://www.slideshare.net/mrzolli/evolution-and-natural-selectionpowerpoint • Tas11244. (2011). Evolution: diversity of life. http://www.slideshare.net/tas11244/darwin-evolution-revised-with-turningpoint-qs • Cinhasler. (2011). Descent with modification- a Darwanian view of life. http://www.slideshare.net/cinhasler/a-pch22 • Highland. N. (2010). Mutation, Evolution and natural selection. http://www.slideshare.net/ismscience/mutation-evolution-and-naturalselection

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