1 / 49

Chapter 13

Chapter 13. 0. How Populations Evolve. 0. Clown, Fool, or Simply Well Adapted? The blue-footed booby Is a type of bird living in the Galápagos Islands. 0. This type of bird possesses many specialized characteristics, called evolutionary adaptations

infinity
Download Presentation

Chapter 13

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 13 0 How Populations Evolve

  2. 0 • Clown, Fool, or Simply Well Adapted? • The blue-footed booby • Is a type of bird living in the Galápagos Islands

  3. 0 • This type of bird possesses many specialized characteristics, called evolutionary adaptations • Which are inherited traits that enhance its ability to survive and reproduce in its particular environment

  4. Figure 13.1A DARWIN’S THEORY OF EVOLUTION 0 • 13.1 A sea voyage helped Darwin frame his theory of evolution • On his visit to the Galápagos Islands • Charles Darwin observed many unique organisms

  5. 0 • Darwin’s main ideas • Can be traced back to the ancient Greeks • Aristotle and the Judeo-Christian culture • Believed that species are fixed

  6. 0 • In the century prior to Darwin • The study of fossils suggested that life forms change • Geologists proposed that a very old Earth • Is changed by gradual processes

  7. 0 NorthAmerica GreatBritain Europe Asia ATLANTICOCEAN PACIFICOCEAN Africa PACIFICOCEAN Equator TheGalápagosIslands PACIFICOCEAN SouthAmerica Pinta Genovesa Australia Marchena Equator Andes Cape ofGood Hope Santiago DaphneIslands Pinzón Fernandina Tasmania NewZealand Cape Horn Isabela SantaCruz SantaFe SanCristobal Tierra del Fuego 40 km 0 Florenza Española Figure 13.1B 40 miles 0 • While on the voyage of the HMS Beagle in the 1830s • Charles Darwin observed similarities between living and fossil organisms and the diversity of life on the Galápagos Islands

  8. 0 • Darwin’s experiences during the voyage of the Beagle • Helped him frame his ideas on evolution

  9. 0 • 13.2 Darwin proposed natural selection as the mechanism of evolution • Darwin observed that organisms • Produce more offspring than the environment can support • Vary in many characteristics that can be inherited

  10. 0 • Darwin reasoned that natural selection • Results in favored traits being represented more and more and unfavored ones less and less in ensuing generations of organisms

  11. Hundreds to thousandsof years of breeding(artificial selection) Ancestral dog (wolf) Figure 13.2B Figure 13.2A 0 • Darwin found convincing evidence for his ideas in the results of artificial selection • The selective breeding of domesticated plants and animals

  12. African wild dog Coyote Jackal Wolf Fox Thousands tomillions of yearsof natural selection Ancestral canine Figure 13.2C 0 • Darwin proposed that living species • Are descended from earlier life forms and that natural selection is the mechanism of evolution

  13. A Skull of Homoerectus B Petrified tree C Ammonite casts D Dinosaur tracks F Insect in amber E Fossilized organicmatter of a leaf G “Ice Man” Figure 13.3A–G 0 • 13.3 The study of fossils provides strong evidence for evolution • Fossils and the fossil record • Strongly support the theory of evolution

  14. Figure 13.3H 0 • The fossil record • Reveals that organisms have evolved in a historical sequence

  15. Figure 13.3I 0 • Many fossils link early extinct species • With species living today

  16. 0 • 13.4 A mass of other evidence reinforces the evolutionary view of life

  17. 0 • Biogeography • Biogeography, the geographic distribution of species • Suggested to Darwin that organisms evolve from common ancestors • Darwin noted that Galápagos animals • Resembled species of the South American mainland more than animals on similar but distant islands

  18. 0 • Comparative anatomy • Comparative anatomy • Is the comparison of body structures in different species • Homology • Is the similarity in characteristics that result from common ancestry

  19. Cat Whale Bat Human Figure 13.4A 0 • Homologous structures • Are features that often have different functions but are structurally similar because of common ancestry

  20. 0 • Comparative Embryology • Comparative embryology • Is the comparison of early stages of development among different organisms

  21. 0 Pharyngealpouches Post-analtail Human embryo Chick embryo Figure 13.4B • Many vertebrates • Have common embryonic structures

  22. Table 13.4 0 • Molecular Biology • Comparisons of DNA and amino acid sequences between different organisms • Reveal evolutionary relationships

  23. A flower mantidin Malaysia A leaf mantid in Costa Rica Figure 13.5A CONNECTION 0 • 13.5 Scientists can observe natural selection in action • Camouflage adaptations that evolved in different environments • Are examples of the results of natural selection

  24. Chromosome with geneconferring resistanceto pesticide Pesticide application Survivor Additionalapplications of thesame pesticide willbe less effective, andthe frequency ofresistant insects inthe populationwill grow Figure 13.5B 0 • Development of pesticide resistance in insects • Is another example of natural selection in action

  25. POPULATION GENETICS AND THE MODERN SYNTHESIS 0 • 13.6 Populations are the units of evolution • A population • Is a group of individuals of the same species living in the same place at the same time • A species is a group of populations • Whose individuals can interbreed and produce fertile offspring

  26. 0 • Population genetics • Studies how populations change genetically over time • The modern synthesis • Connects Darwin’s theory with population genetics

  27. 0 • A gene pool • Is the total collection of genes in a population at any one time • Microevolution • Is a change in the relative frequencies of alleles in a gene pool

  28. Webbing No webbing Figure 13.7A 0 • 13.7 The gene pool of a nonevolving population remains constant over the generations • In a nonevolving population • The shuffling of alleles that accompanies sexual reproduction does not alter the genetic makeup of the population

  29. Phenotypes Genotypes WW Ww ww Number of animals(total  500) 320 160 20 160 500 20 500 320 500 Genotype frequencies  0.32  0.04  0.64 Number of allelesin gene pool(total  1,000) 640 W 160 W 160 w 40 w 800 1,000 200 1,000  0.8 W  0.2 w Allele frequencies Figure 13.7B 0 • Hardy-Weinberg equilibrium • States that the shuffling of genes during sexual reproduction does not alter the proportions of different alleles in a gene pool

  30. Recombinationof alleles fromparent generation SPERM W spermp 0.8 w spermq 0.2 Wwpq 0.16 WWp2 0.64 W eggp 0.8 EGGS wwq2 0.04 wWqp 0.16 w eggq 0.2 Next generation: 0.04 ww Genotype frequencies 0.64 WW 0.32 Ww 0.2 w Allele frequencies 0.8 W Figure 13.7C 0 • We can follow alleles in a population • To observe if Hardy-Weinberg equilibrium exists

  31. 0 • For a population to be in Hardy-Weinberg equilibrium, it must satisfy five main conditions • The population is very large • The population is isolated • Mutations do not alter the gene pool • Mating is random • All individuals are equal in reproductive success

  32. CONNECTION 0 • 13.8 The Hardy-Weinberg equation is useful in public health science • Public health scientists use the Hardy-Weinberg equation • To estimate frequencies of disease-causing alleles in the human population

  33. 0 • 13.9 In addition to natural selection, genetic drift and gene flow can contribute to evolution • Genetic drift • Is a change in the gene pool of a population due to chance • Can alter allele frequencies in a population

  34. Originalpopulation Bottleneckingevent Survivingpopulation Figure 13.9B Figure 13.9A 0 • Genetic drift • Can cause the bottleneck effect or the founder effect

  35. 0 • Gene flow • Is the movement of individuals or gametes between populations • Can alter allele frequencies in a population

  36. 0 • Natural selection • Leads to differential reproductive success in a population • Can alter allele frequencies in a population

  37. CONNECTION 0 • 13.10 Endangered species often have reduced variation • Low genetic variability • May reduce the capacity of endangered species to survive as humans continue to alter the environment Figure 13.10

  38. Figure 13.11 VARIATION AND NATURAL SELECTION 0 • 13.11 Variation is extensive in most populations • Many populations exhibit polymorphism • Different forms of phenotypic characteristics

  39. 0 • Populations may also exhibit geographic variation • Variation of an inherited characteristic along a geographic continuum

  40. 0 • 13.12 Mutation and sexual recombination generate variation • Mutations, or changes in the nucleotide sequence of DNA • Can create new alleles

  41. A1 A1 A2 A3 Parents X Meiosis A2 A1 A3 Gametes Fertilization A2 A1 Offspring,with newcombinationsof alleles A1 A3 and Figure 13.12 0 • Sexual recombination • Generates variation by shuffling alleles during meiosis

  42. CONNECTION 0 • 13.13 The evolution of antibiotic resistance in bacteria is a serious public health concern • The excessive use of antibiotics • Is leading to the evolution of antibiotic-resistant bacteria Colorized SEM 5,600 Figure 13.13

  43. 0 • 13.14 Diploidy and balancing selection variation • Diploidy preserves variation • By “hiding” recessive alleles • Balanced polymorphism • May result from the heterozygote advantage or frequency-dependent selection

  44. Figure 13.14 0 • Some variations may be neutral • Providing no apparent advantage or disadvantage

  45. 0 • 13.15 The perpetuation of genes defines evolutionary fitness • An individual’s fitness • Is the contribution it makes to the gene pool of the next generation

  46. 0 • 13.16 Natural selection can alter variation in a population in three ways • Stabilizing selection • Favors intermediate phenotypes • Directional selection • Acts against individuals at one of the phenotypic extremes • Disruptive selection • Favors individuals at both extremes of the phenotypic range

  47. Originalpopulation Frequency of individuals Phenotypes (fur color) Originalpopulation Evolvedpopulation Figure 13.16 Stabilizing selection Disruptive selection Directional selection 0 • Three possible effects of natural selection

  48. Figure 13.17B Figure 13.17A 0 • 13.17 Sexual selection may produce sexual dimorphism • Sexual selection leads to the evolution of secondary sexual characteristics • Which may give individuals an advantage in mating

  49. 0 • 13.18 Natural selection cannot fashion perfect organisms • There are at least four reasons why natural selection cannot produce perfection • Organisms are limited by historical constraints • Adaptations are often compromises • Chance and natural selection interact • Selection can only edit existing variations

More Related