Biodiversity and Evolution

1. Biodiversity and Evolution Chapter 4

2. The American Alligator

3. Core Case Study: Why Should We Care about the American Alligator? • Largest reptile in North America • 1930s: Hunters and poachers (sport, bellies, meat) • 90% killed off • Importance of gator holes, nesting mounds, pathways • Water resource, nesting sites for others, gar • 1967: endangered species • 1977: comeback, threatened species

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 • Vital renewable resource • food, wood fibers, energy, medicine • Waste and pest control

6. Natural Capital: Major Components of the Earth’s Biodiversity

7. Different types of diversity • Species diversity • Ecosystem diversity • Functional diversity: • variety in the processes and energy flow in an ecosystem: extra uses of nests, paths of gators • Genetic Diversity • Variety in traits

8. 4-2 Where Do Species Come From? • 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).

9. Biological Evolution by Natural Selection Explains How Life Changes over Time • Biological evolution • Natural selection Constant struggle for food, resources to survive Some individuals have advantage over others Those with tend to have more successful offspring Charles Darwin • (gathered evidence AND published) Alfred Russel Wallace • Tree of Life

10. Six Major Kingdoms of Species as a Result of Natural Selection

11. Prokaryotes Eukaryotes Plants Eubacteria Archaebacteria Fungi Animals Protists 0 First humans Cenozoic Extinction of dinosaurs Mesozoic Plants colonize land Paleozoic 500 Origin of multicellular organisms 1,000 1,500 Oldest eukaryotic fossils 2,000 Millions of years ago Accumulation of O2 in atmosphere from photosynthetic cyanobacterium 2,500 Precambrian 3,000 Oldest prokaryotic fossils 3,500 4,000 Earth cool enough for crust to solidify Origin of Earth 4,500 Fig. 4-3, p. 81

12. Animation: Evolutionary tree of life

13. Animation: Evolutionary tree diagrams

14. The Fossil Record Tells Much of the Story of Evolution • Fossils • Physical evidence of ancient organisms • Bones, casts, tracks… • Some reveal what their internal structures looked like, some their actions • Fossil record is incomplete: why?

15. Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era

16. Video: Dinosaur discovery

17. The Genetic Makeup of a Population Can Change • Populations evolve by becoming genetically different • Genetic variations • First step in biological evolution • Occurs through mutations in reproductive cells • Mutations in other cells can happen , but only reproductive cell mutations are passed on • Sometimes a mutation can result in a new genetic trait that gives it a better chance to survive • “Waterworld” with Kevin Costner

18. Animation: Adaptive trait

19. Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring • Natural selection: acts on individuals • Second step in biological evolution • Adaptation may lead to differential reproduction • Genetic resistance • When environmental conditions change, populations • Adapt • Migrate • Become extinct

20. Evolution by Natural Selection

21. 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 Fig. 4-5, p. 83

22. 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. 4-5, p. 83

23. Animation: Modeling genetic drift

24. Humans and Natural Selection • Is it still going on? Evidence • Traits that might lead to differential production • Do the number of offspring matter for human adaptation?

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

26. Adaptation through Natural Selection Has Limits • Genetic change must precede change in the environmental conditions • Reproductive capacity • How many • How fast

27. 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

28. There is a grandeur to this view of life…While this planet has gone cycling on… Endless forms most beautiful and wonderfulhave been and are beingevolved Charles Darwin

29. Evolution Timeline Project/Lab

30. Meeting with an evolutionary biologist

31. Video: Creation vs. evolution

32. Animation: Disruptive selection

33. Animation: Change in moth population

34. Animation: Stabilizing selection

35. 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.

36. Geologic Processes Affect Natural Selection • Tectonic plates affect evolution and the location of life on earth • Location of continents and oceans • Species physically move, or adapt, or form new species through natural selection • Tectonic actions: Earthquakes, Volcanic eruptions can have profound effects on natural selection • Pollution • Change in ecosystem

37. 225 million years ago 135 million years ago 65 million years ago Present Stepped Art Fig. 4-6, p. 85

38. Animation: Continental drift

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

40. Changes in Ice Coverage in the Northern Hemisphere During the last 18,000 Years

41. Science Focus: Earth Is Just Right for Life to Thrive • Certain temperature range • Dependence on water • Rotation on its axis • Revolution around the sun • Enough gravitational mass

42. Animation: Stanley Miller's experiment

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 premature extinction of species and by destroying or degrading habitats needed for the development of new species.

44. Speciation • Two species arise from one • Environments change for 2 groups of same species • Change progresses to point where breeding produces sterile offspring

45. Animation: Speciation on an archipelago

46. Geographic Isolation Can Lead to Reproductive Isolation

47. Extinction is Forever • Extinction • Background 1:5,000,000 • Mass >25% • 3-5 events in history with mass extinction and low speciation • Endemic species • Specialized • Found in only one location • Particularly vulnerable

48. Video: Frogs galore

49. Golden Toad of Costa Rica, Extinct

50. Science Focus: Humans Have Two Ways to Change the Genetic Traits of Populations • Artificial selection • Genetic engineering, gene splicing • Consider • Ethics • Morals • Privacy issues • Harmful effects