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  • Figure 13.1a Camouflage as an example of evolutionary adaptation: Trinidad tree mantid
  • Figure 13.1b Camouflage as an example of evolutionary adaptation: leaf mantid
  • Figure 13.1c Camouflage as an example of evolutionary adaptation: flower mantid
  • Figure 13.2 The historical context of Darwin's life and ideas
  • Figure 13.3 The voyage of the Beagle
  • Figure 13.3a Charles Darwin in 1840
  • Figure 13.3b The HMS Beagle
  • Figure 13.3c The Galápagos Islands
  • Figure 13.10 Genetic relationships among some primates
  • Figure 13.11a Galápagos finches with beaks adapted for specific diets: large ground finch
  • Figure 13.11b Galápagos finches with beaks adapted for specific diets: small tree finch
  • Figure 13.11c Galápagos finches with beaks adapted for specific diets: woodpecker finch
  • Figure 13.14 Evolution of pesticide resistance in insect populations (Step 1)
  • Figure 13.14 Evolution of pesticide resistance in insect populations (Step 2)
  • Figure 13.14 Evolution of pesticide resistance in insect populations (Step 3)
  • Figure 13.16 An evolutionary tree of tetrapods
  • Figure 13.20 A mathematical swim in the gene pool
  • Figure 13.21 A warning to individuals with PKU
  • Figure 13.23 Bottleneck effect (Step 1)
  • Figure 13.23 Bottleneck effect (Step 2)
  • Figure 13.23 Bottleneck effect (Step 3)
  • Figure 13.25a Residents of Tristan da Cunha in the early 1900s
  • Figure 13.25b Location of Tristan da Cunha
  • Figure 13.26 Human gene flow
  • Figure 13.27 Darwinian fitness of some flowering plants depends in part on competition in attracting pollinators
  • Figure 13.28 Three general effects of natural selection on a phenotypic character
  • Figure 13.UN2 Hardy-Weinberg formula
  • Figure 13.UN3 Summary: Darwin's observations and conclusion
  • 13 lecture presentation0

    1. 1. Biology and Society: Persistent Pests • Mosquitoes and malaria – In the 1960s, the World Health Organization (WHO) began a campaign to eradicate the mosquitoes that transmit malaria. – It used DDT, to which some mosquitoes have evolved resistance. © 2010 Pearson Education, Inc.
    2. 2. © 2010 Pearson Education, Inc. • The evolution of pesticide-resistant insects is just one of the ways that evolution affects our lives. • An understanding of evolution informs every field of biology, for example: – Agriculture – Medicine – Biotechnology – Conservation biology
    3. 3. © 2010 Pearson Education, Inc. CHARLES DARWIN AND THE ORIGIN OF SPECIES • Charles Darwin published On the Origin of Species by Means of Natural Selection, November 24, 1859. • Darwin presented two main concepts: – Life evolves – Change occurs as a result of “descent with modification,” with natural selection as the mechanism
    4. 4. © 2010 Pearson Education, Inc. • Natural selection is a process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are individuals with other characteristics.
    5. 5. A Trinidad tree mantid that mimics dead leaves Figure 13.1a
    6. 6. A leaf mantid in Costa Rica Figure 13.1b
    7. 7. A flower mantid in Malaysia Figure 13.1c
    8. 8. © 2010 Pearson Education, Inc. • Natural selection leads to: – A population (a group of individuals of the same species living in the same place at the same time) changing over generations – Evolutionary adaptation
    9. 9. 1809 Lamarck publishes his theory of evolution. 1830 Lyell publishes Principles of Geology. 1837 Darwin begins analyzing his specimens and writing his notebooks on the origin of species. 1844 Darwin writes his essay on the origin of species. 1865 Mendel publishes papers on genetics. 1858 Wallace sends an account of his theory to Darwin. 1859 Darwin publishes The Origin of Species. 1809 Charles Darwin is born. 1831–36 Darwin travels around the world on the HMS Beagle. Green sea turtle in the Galápagos Islands 1800 1870 Figure 13.2
    10. 10. © 2010 Pearson Education, Inc. The Idea of Fixed Species • The Greek philosopher Aristotle held the belief that species are fixed and do not evolve. • The Judeo-Christian culture fortified this idea with a literal interpretation of the Bible and suggested the Earth may only be 6,000 years old.
    11. 11. © 2010 Pearson Education, Inc. The Voyage of the Beagle • Darwin was born on February 12, 1809, the same day that Abraham Lincoln was born. • In December 1831 Darwin left Great Britain on the HMS Beagle on a five-year voyage around the world. Video: Galápagos Islands Overview
    12. 12. Darwin in 1840 Galápagos Islands North America South America PACIFIC OCEAN PACIFIC OCEAN ATLANTIC OCEAN Pinta 40 miles 40 km0 Florenza 0 Fernandina Marchena Genovesa Equator Santiago Daphne Islands Pinzón Española Isabela Santa Cruz Santa Fe San Cristobal Great Britain Cape of Good Hope Europe Africa Cape Horn Tierra del Fuego Equator Asia HMS Beagle Australia Tasmania New Zealand Andes Figure 13.3
    13. 13. Darwin in 1840 Figure 13.3a
    14. 14. HMS Beagle Figure 13.3b
    15. 15. Galápagos Islands PACIFIC OCEANPinta 40 miles 40 km0 Florenza 0 Fernandina Marchena Genovesa Equator Santiago Daphne Islands Pinzón Española Isabela Santa Cruz Santa Fe San Cristobal Figure 13.3c
    16. 16. © 2010 Pearson Education, Inc. • On his journey on the Beagle, Darwin: – Collected thousands of specimens – Observed various adaptations in organisms
    17. 17. © 2010 Pearson Education, Inc. • Darwin was strongly influenced by the writings of geologist Charles Lyell. • Lyell suggested that the Earth: – Is very old – Was sculpted by gradual geological processes that continue today • Darwin applied Lyell’s principle of gradualism to the evolution of life on Earth.
    18. 18. © 2010 Pearson Education, Inc. Descent with Modification • Darwin made two main points in The Origin of Species: – Organisms inhabiting Earth today descended from ancestral species – Natural selection was the mechanism for descent with modification
    19. 19. © 2010 Pearson Education, Inc. EVIDENCE OF EVOLUTION • Biological evolution leaves observable signs. • We will examine five of the many lines of evidence in support of evolution: – The fossil record – Biogeography – Comparative anatomy – Comparative embryology – Molecular biology
    20. 20. © 2010 Pearson Education, Inc. The Fossil Record • Fossils are: – Imprints or remains of organisms that lived in the past – Often found in sedimentary rocks
    21. 21. © 2010 Pearson Education, Inc. • The fossil record: – Is the ordered sequence of fossils as they appear in rock layers – Reveals the appearance of organisms in a historical sequence – Fits the molecular and cellular evidence that prokaryotes are the ancestors of all life Video: Grand Canyon
    22. 22. © 2010 Pearson Education, Inc. • Paleontologists: – Are scientists that study fossils – Have discovered many transitional forms that link past and present
    23. 23. © 2010 Pearson Education, Inc. Biogeography • Biogeography is the study of the geographic distribution of species that first suggested to Darwin that today’s organisms evolved from ancestral forms.
    24. 24. © 2010 Pearson Education, Inc. Comparative Anatomy • Comparative anatomy – Is the comparison of body structure between different species – Confirms that evolution is a remodeling process
    25. 25. © 2010 Pearson Education, Inc. Molecular Biology • The hereditary background of an organism is documented in: – Its DNA – The proteins encoded by the DNA • Evolutionary relationships among species can be determined by comparing: – Genes – Proteins of different organisms
    26. 26. Percent of selected DNA sequences that match a chimpanzee’s DNA Chimpanzee 100%96%92% Human Gibbon Orangutan Gorilla Primate Old World monkey Figure 13.10
    27. 27. © 2010 Pearson Education, Inc. NATURAL SELECTION • Darwin noted the close relationship between adaptation to the environment and the origin of new species. • The evolution of finches on the Galápagos Islands is an excellent example.
    28. 28. (a) The large ground finch Figure 13.11a
    29. 29. (b) The small tree finch Figure 13.11b
    30. 30. (c) The woodpecker finch Figure 13.11c
    31. 31. © 2010 Pearson Education, Inc. Darwin’s Theory of Natural Selection • Darwin based his theory of natural selection on two key observations: – All species tend to produce excessive numbers of offspring – Organisms vary, and much of this variation is heritable
    32. 32. © 2010 Pearson Education, Inc. Natural Selection in Action • Examples of natural selection include: – Pesticide-resistant insects – Antibiotic-resistant bacteria – Drug-resistant strains of HIV Blast Animation: Natural Selection Blast Animation: Evidence for Evolution: Antibiotic Resistance in Bacteria
    33. 33. Chromosome with gene conferring resistance to pesticide Insecticide application Figure 13.14-1
    34. 34. Chromosome with gene conferring resistance to pesticide Insecticide application Figure 13.14-2
    35. 35. Chromosome with gene conferring resistance to pesticide Reproduction Survivors Insecticide application Figure 13.14-3
    36. 36. EVOLUTIONARY TREES • Darwin saw the history of life as analogous to a tree: – The first forms of life on Earth form the common trunk – At each fork is the last common ancestor to all the branches extending from that fork © 2010 Pearson Education, Inc.
    37. 37. Tetrapod limbs Amnion Feathers Lungfishes Mammals Amphibians Lizards and snakes Crocodiles Hawks and other birds Ostriches Amniotes Tetrapods Birds Figure 13.16
    38. 38. The Modern Synthesis: Darwinism Meets Genetics • The modern synthesis is the fusion of genetics with evolutionary biology. © 2010 Pearson Education, Inc.
    39. 39. © 2010 Pearson Education, Inc. Populations as the Units of Evolution • A population is: – A group of individuals of the same species, living in the same place, at the same time – The smallest biological unit that can evolve
    40. 40. © 2010 Pearson Education, Inc. • The total collection of alleles in a population at any one time is the gene pool. • When the relative frequency of alleles changes over a number of generations, evolution is occurring on its smallest scale, which is sometimes called microevolution.
    41. 41. © 2010 Pearson Education, Inc. Sources of Genetic Variation • Genetic variation results from: – Mutations, changes in the DNA of an organism – The shuffling of alleles during meiosis
    42. 42. © 2010 Pearson Education, Inc. Analyzing Gene Pools • The gene pool is a reservoir from which the next generation draws its genes. • Alleles in a gene pool occur in certain frequencies.
    43. 43. © 2010 Pearson Education, Inc. • Alleles can be symbolized by: – p for the relative frequency of the dominant allele in the population – q for the frequency of the recessive allele in the population
    44. 44. © 2010 Pearson Education, Inc. • Genotype frequencies: – Can be calculated from allele frequencies – Are symbolized by the expressions p2 , 2pq, and q2
    45. 45. Allele frequencies Genotype frequencies Sperm Eggs p = 0.8 (R) q = 0.2 (r) p = 0.8 R q = 0.2 r RR p = 0.8 R q = 0.2 r p2 = 0.64 rR qp = 0.16 q2 = 0.04 rr pq = 0.16 Rr (RR)p2 = 0.64 q2 = 0.04(rr) 2pq = 0.32 (Rr) Figure 13.20
    46. 46. © 2010 Pearson Education, Inc. • The Hardy-Weinberg formula can be used to calculate the frequencies of genotypes in a gene pool from the frequencies of alleles.
    47. 47. © 2010 Pearson Education, Inc. Population Genetics and Health Science • The Hardy-Weinberg formula can be used to calculate the percentage of a human population that carries the allele for a particular inherited disease.
    48. 48. © 2010 Pearson Education, Inc. • PKU: – Is a recessive allele that prevents the breakdown of the amino acid phenylalanine – Occurs in about one out of every 10,000 babies born in the United States
    49. 49. INGREDIENTS: SORBITOL, MAGNESIUM STEARATE, ARTIFICIAL FLAVOR, ASPARTAME† (SWEETENER), ARTIFICIAL COLOR (YELLOW 5 LAKE, BLUE 1 LAKE), ZINC GLUCONATE. † PHENYLKETONURICS: CONTAINS PHENYLALANINE Figure 13.21
    50. 50. © 2010 Pearson Education, Inc. Microevolution as Change in a Gene Pool • How can we tell if a population is evolving? • A non-evolving population is in genetic equilibrium, called the Hardy-Weinberg equilibrium, in which the population gene pool remains constant over time.
    51. 51. © 2010 Pearson Education, Inc. • From a genetic perspective evolution can be defined as a generation-to-generation change in a population’s frequencies of alleles, sometimes called microevolution.
    52. 52. © 2010 Pearson Education, Inc. MECHANISMS OF EVOLUTION • The main causes of evolutionary change are: – Genetic drift – Gene flow – Natural selection
    53. 53. © 2010 Pearson Education, Inc. Genetic Drift • Genetic drift is: – A change in the gene pool of a small population – Due to chance Animation: Causes of Evolutionary Change
    54. 54. © 2010 Pearson Education, Inc. The Bottleneck Effect • The bottleneck effect: – Is an example of genetic drift – Results from a drastic reduction in population size
    55. 55. Original population Figure 13.23-1
    56. 56. Original population Bottlenecking event Figure 13.23-2
    57. 57. Original population Bottlenecking event Surviving population Figure 13.23-3
    58. 58. © 2010 Pearson Education, Inc. • Bottlenecking in a population usually reduces genetic variation because at least some alleles are likely to be lost from the gene pool.
    59. 59. © 2010 Pearson Education, Inc. The Founder Effect • The founder effect is likely when a few individuals colonize an isolated habitat and represent genetic drift in a new colony.
    60. 60. • The founder effect explains the relatively high frequency of certain inherited disorders among some small human populations. © 2010 Pearson Education, Inc.
    61. 61. Figure 13.25a
    62. 62. South America Tristan da Cunha Africa Figure 13.25b
    63. 63. © 2010 Pearson Education, Inc. Gene Flow • Gene flow: – Is genetic exchange with another population – Tends to reduce genetic differences between populations
    64. 64. Figure 13.26
    65. 65. © 2010 Pearson Education, Inc. Natural Selection: A Closer Look • Of all causes of microevolution, only natural selection promotes adaptation.
    66. 66. © 2010 Pearson Education, Inc. Darwinian Fitness • Fitness is the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals. Video: Wolves Agonistic Behavior
    67. 67. Figure 13.27
    68. 68. © 2010 Pearson Education, Inc. Three General Outcomes of Natural Selection • Directional selection: – Shifts the phenotypic “curve” of a population – Selects in favor of some extreme phenotype • Disruptive selection can lead to a balance between two or more contrasting phenotypic forms in a population.
    69. 69. © 2010 Pearson Education, Inc. • Stabilizing selection: – Favors intermediate phenotypes – Is the most common
    70. 70. Original population Evolved population Phenotypes (fur color) Frequency ofindividualsOriginal population (a) Directional selection (b) Disruptive selection (c) Stabilizing selection Figure 13.28
    71. 71. Frequency of heterozygotes Frequency of homozygotes for alternate allele Frequency of homozygotes for one allele Figure 13.UN2
    72. 72. Individual variation Overproduction of offspring Observations Natural selection: unequal reproductive success Conclusion Figure 13.UN3

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