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CHAPTER 4 Biodiversity and Evolution

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  1. CHAPTER 4 Biodiversity and Evolution

  2. Core Case Study: Why Should We Protect Sharks? • 400 known species • 6 deaths per year from shark attacks • 79-97 million sharks killed every year • Fins • Organs, meat, hides • Fear • 32% shark species threatened with extinction • Keystone species • Cancer resistant

  3. Threatened Sharks Fig. 4-1, p. 80

  4. 4-1 What Is Biodiversity and Why Is It Important? • Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth.

  5. Biodiversity Is a Crucial Part of the Earth’s Natural Capital (1) • Species: set of individuals who can mate and produce fertile offspring • 8 million to 100 million species • 1.9 million identified • Unidentified are mostly in rain forests and oceans

  6. Biodiversity Is a Crucial Part of the Earth’s Natural Capital (2) • Species diversity • Genetic diversity • Ecosystem diversity • Biomes: regions with distinct climates/species • Functional diversity • Biodiversity is an important part of natural capital

  7. Classifying Homo Sapiens Supplement 5, Fig. 2, p. S19

  8. Natural Capital: Major Components of the Earth’s Biodiversity Fig. 4-2, p. 82

  9. Functional Diversity The biological and chemical processes such as energy flow and matter recycling needed for the survival of species, communities, and ecosystems. Ecological Diversity The variety of terrestrial and aquatic ecosystems found in an area or on the earth. Solar energy Chemical nutrients (carbon dioxide, oxygen, nitrogen, minerals) Heat Heat Heat Decomposers (bacteria, fungi) Producers (plants) Consumers (plant eaters, meat eaters) Heat Heat Genetic Diversity The variety of genetic material within a species or a population. Species Diversity The number and abundance of species present in different communities. Fig. 4-2, p. 82

  10. Two Species: Columbine Lily and Great Egret Fig. 4-3, p. 82

  11. Genetic Diversity Fig. 4-4, p. 83

  12. Major Biomes Fig. 4-5, p. 84

  13. Denver Baltimore San Francisco Las Vegas St. Louis Coastal mountain ranges Sierra Nevada Great American Desert Rocky Mountains Great Plains Mississippi River Valley Appalachian Mountains Coastal chaparral and scrub Coniferous forest Desert Coniferous forest Prairie grassland Deciduous forest Fig. 4-5, p. 84

  14. Science Focus: Have You Thanked the Insects Today? • Bad rep: sting us, bite us, spread disease, eat our food, invade plants • Pollination: lets flowering plants reproduce sexually • Free pest control: insects eat other insects • We need insects more than they need us

  15. Importance of Insects Fig. 4-A, p. 83

  16. Individuals Matter: Edward O. Wilson: A Champion of Biodiversity • Loved bugs as a kid • Specialized in ants • Widened scope to earth’s biodiversity • Theory of island biogeography • First to use “biodiversity” in a scientific paper

  17. Edward O. Wilson Fig. 4-B, p. 85

  18. 4-2 How Does the Earth’s Life Change Over Time? • Concept 4-2A The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations. • Concept 4-2B Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

  19. Biological Evolution by Natural Selection Explains How Life Changes over Time (1) • Fossils • Physical evidence of ancient organisms • Reveal what their external structures looked like • Fossil record: entire body of fossil evidence • Only have fossils of 1% of all species that lived on earth

  20. Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era Fig. 4-6, p. 86

  21. Biological Evolution by Natural Selection Explains How Life Changes over Time (2) • Biological evolution: how earth’s life changes over time through changes in the genetic characteristics of populations • Darwin: Origin of Species • Natural selection: individuals with certain traits are more likely to survive and reproduce under a certain set of environmental conditions • Huge body of evidence

  22. Evolution of Life on Earth Supplement 5, Fig. 2, p. S18

  23. Evolution by Natural Selection Works through Mutations and Adaptations (1) • Populations evolve by becoming genetically different • Genetic variations • First step in biological evolution • Occurs through mutations in reproductive cells • Mutations: random changes in DNA molecules

  24. Evolution by Natural Selection Works through Mutations and Adaptations (2) • Natural selection: acts on individuals • Second step in biological evolution • Adaptation may lead to differential reproduction • Genetic resistance: ability of one or more members of a population to resist a chemical designed to kill it

  25. Evolution by Natural Selection Fig. 4-7, p. 87

  26. (a) A group of bacteria, including genetically resistant ones, are exposed to an antibiotic (d) Eventually the resistant strain replaces all or most of the strain affected by the antibiotic (c) The genetically resistant bacteria start multiplying (b) Most of the normal bacteria die Normal bacterium Resistant bacterium Fig. 4-7, p. 87

  27. A group of bacteria, including genetically resistant ones, are exposed to an antibiotic Eventually the resistant strain replaces the strain affected by the antibiotic The genetically resistant bacteria start multiplying Most of the normal bacteria die Normal bacterium Resistant bacterium Stepped Art Fig. 4-7, p. 87

  28. Case Study: How Did Humans Become Such a Powerful Species? • Strong opposable thumbs • Walk upright • Complex brain

  29. Adaptation through Natural Selection Has Limits • Adaptive genetic traits must precede change in the environmental conditions • Reproductive capacity • Species that reproduce rapidly and in large numbers are better able to adapt

  30. Three Common Myths about Evolution through Natural Selection • “Survival of the fittest” is not “survival of the strongest” • Organisms do not develop traits out of need or want • No grand plan of nature for perfect adaptation

  31. 4-3 How Do Geological Processes and Climate Change Affect Evolution? • Concept 4-3 Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.

  32. Geologic Processes Affect Natural Selection • Tectonic plates affect evolution and the location of life on earth • Locations of continents and oceans have shifted • Species physically move, or adapt, or form new species through natural selection • Earthquakes • Volcanic eruptions

  33. Movement of the Earth’s Continents over Millions of Years Fig. 4-8, p. 89

  34. 225 million years ago Fig. 4-8, p. 89

  35. 135 million years ago Fig. 4-8, p. 89

  36. 65 million years ago Fig. 4-8, p. 89

  37. Present Fig. 4-8, p. 89

  38. 225 million years ago 135 million years ago 65 million years ago Present Stepped Art Fig. 4-8, p. 89

  39. Climate Change and Catastrophes Affect Natural Selection • Ice ages followed by warming temperatures • Collisions between the earth and large asteroids • New species • Extinctions

  40. Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years Fig. 4-9, p. 89

  41. Northern Hemisphere Ice coverage Modern day (August) 18,000 years before present Legend Continental ice Sea ice Land above sea level Fig. 4-9, p. 89

  42. Science Focus: Earth Is Just Right for Life to Thrive • Temperature range: supports life • Orbit size: moderate temperatures • Liquid water: necessary for life • Rotation speed: sun doesn’t overheat surface • Size: gravity keeps atmosphere

  43. 4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity? • Concept 4-4A As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth’s biodiversity. • Concept 4-4B Human activities can decrease biodiversity by causing the extinction of many species and by destroying or degrading habitats needed for the development of new species.

  44. How Do New Species Evolve? • Speciation: one species splits into two or more species • Geographic isolation: happens first; physical isolation of populations for a long period • Reproductive isolation: mutations and natural selection in geographically isolated populations lead to inability to produce viable offspring when members of two different populations mate

  45. Geographic Isolation Can Lead to Reproductive Isolation Fig. 4-10, p. 91

  46. Adapted to cold through heavier fur, short ears, short legs, and short nose. White fur matches snow for camouflage. Arctic Fox Northern population Different environmental conditions lead to different selective pressures and evolution into two different species. Spreads northward and southward and separates Early fox population Gray Fox Southern population Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Fig. 4-10, p. 91

  47. Extinction is Forever • Extinction • Biological extinction • Local extinction • Endemic species • Found only in one area • Particularly vulnerable • Background extinction: typical low rate of extinction • Mass extinction: 3-5 over 500 million years

  48. Golden Toad of Costa Rica, Extinct Fig. 4-11, p. 92

  49. Science Focus: Changing the Genetic Traits of Populations • Artificial selection • Use selective breeding/crossbreeding • Genetic engineering, gene splicing • Consider • Ethics • Morals • Privacy issues • Harmful effects

  50. Artificial Selection Fig. 4-C, p. 92