1. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lectures by Chris C. Romero PowerPoint ® Lectures for Essential Biology, Third Edition – Neil Campbell, Jane Reece, and Eric Simon Essential Biology with Physiology, Second Edition – Neil Campbell, Jane Reece, and Eric Simon CHAPTER 20 Human Impact on the Environment

6. Biology and Society: Aquarium Menaces In May 2002, a fisher in Maryland caught and released an exotic looking fish, which was identified as the northern snakehead. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

7. Figure 20.1a

8. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The northern snakehead –Is a fish native to eastern Asia. –Was accidentally introduced into Maryland. Introduced species –Can severely disrupt ecosystems.

9. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The seaweed Caulerpa –Was accidentally introduced into the United States, probably after being dumped from a home aquarium. –Has caused significant problems and competes with native species.

10. Figure 20.1b

11. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Human Impact on Biological Communities Human disturbance of biological communities is almost always destructive.

12. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Human Disturbance of Communities Of all animals, humans have the greatest impact on communities worldwide.

13. Figure 20.2

14. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Much of the United States is now a hodgepodge of early successional growth where more mature communities once prevailed. Human disturbance usually reduces species diversity in communities.

15. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Introduced Species Introduced species –Are those that humans intentionally or accidentally move from the species’ native locations to new geographic regions.

16. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Kudzu, a Japanese plant –Was introduced into the United States in 1930 as a means of erosion control. –Has taken over vast expanses of the southern landscape.

17. Figure 20.3a

18. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The European starling –Was introduced into the United States by a group intent on introducing all the plants and animals mentioned in Shakespeare’s plays. –Has displaced many native songbirds.

19. Figure 20.3b

20. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Argentine ants –Were accidentally introduced into the United States. –Have decimated populations of native ants in California.

21. Figure 20.3c

22. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The zebra mussel –Was accidentally introduced into the United States, probably in ballast water from a cargo ship. –Has caused significant problems and competes with native species.

23. Figure 20.3d

24. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Human Impact on Ecosystems Human population growth and technology add up to a badly bruised biosphere.

25. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The carbon dioxide exhaust of our machinery –Is probably causing a global warming that will affect all life on Earth.

26. Figure 20.4

27. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Impact on Chemical Cycles Human activities –Often intrude in biogeochemical cycles by removing nutrients from one location and adding them to another.

28. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Impact on the Carbon Cycle The increased burning of fossil fuels –Is steadily raising the level of CO 2 in the atmosphere. –Is leading to significant environmental problems, such as global warming.

29. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Impact on the Nitrogen Cycle Sewage treatment facilities and fertilizers –Add large amounts of nitrogen to aquatic systems, causing heavy growth of algae.

30. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Impact on the Phosphorous Cycle Sewage treatment facilities and fertilizers –Also add large amounts of phosphates to aquatic systems, causing eutrophication of lakes.

31. Figure 20.5

32. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Impact on the Water Cycle Destruction of tropical rain forest –Will change the amount of water vapor in the air. –May alter local and global weather patterns.

33. Figure 20.6

34. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings To irrigate crops, humans pump large amounts of ground water to the surface. Deforestation and extensive removal of ground water change the water cycle.

35. The Process of Science: Does Deforestation Change Chemical Cycles? The Hubbard Brook Experimental Forest is a study site for chemical cycling in a forest ecosystem. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

36. Researchers have monitored water and mineral loss by damming parts of a creek in the forest.

37. Figure 20.7a

38. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings One valley was completely deforested, –And the inflow and outflow of water and minerals was compared to a control area.

39. Figure 20.7b

40. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Net losses of minerals from the altered area were huge, exhibiting the impact of human activity on a forest ecosystem.

41. Figure 20.7c

42. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Release of Toxic Chemicals to Ecosystems Humans have added to ecosystems new toxic materials, which often cannot be degraded by microorganisms.

43. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Toxic substances –Are acquired by organisms from the environment along with nutrients and water. –May be metabolized, but can also accumulate in specific tissues.

44. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Biological magnification –Is a process in which toxins become more concentrated in successive trophic levels of a food web.

45. Figure 20.8

46. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Human Impact on the Atmosphere and Climate It was once thought that the atmosphere could absorb the variety of gaseous waste products produced by humans.

47. Figure 20.9

48. Carbon Dioxide Emissions, the Greenhouse Effect, and Global Warming Since the Industrial Revolution, the concentration of CO 2 in the atmosphere has been increasing due to the burning of fossil fuels and wood and to deforestation. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

49. Figure 20.10

50. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The greenhouse effect –Retains solar heat in the atmosphere. –Is produced by CO 2 and water vapor in the atmosphere.

51. Figure 20.11

52. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The marked increase in atmospheric CO 2 could cause an increase in global temperatures, with potentially disastrous consequences.

53. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Developed countries –Have the greatest energy consumption. –Have the greatest responsibility to reduce energy consumption.

54. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Depletion of Atmospheric Ozone The ozone layer –Absorbs UV radiation, preventing much of it from contacting organisms in the biosphere.

55. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The protective ozone layer –Has been thinning since 1975 because of the accumulation of chlorofluorocarbons.

56. Figure 20.12

57. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The consequences of ozone depletion –May be quite severe for all life on Earth, including humans.

58. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Biodiversity Crisis The effect of human activity on communities and ecosystems is an alarming biodiversity crisis, a precipitous decline in Earth’s great variety of life.

59. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Three Levels of Biodiversity Biodiversity has three main components.

60. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The first is the diversity of ecosystems. The second is the variety of species that make up the biological community of any ecosystem.

61. Figure 20.13

62. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The third is the genetic variation within each species.

63. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Loss of Species The current mass extinction –Is being caused by human activity. –Is broader and faster than other past extinctions.

64. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings We do not know the full scale of the biodiversity crisis. –However, there are enough signs to know that the biosphere is in deep trouble.

65. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings 12% of the known bird species in the world and 24% of the known mammal species are threatened with extinction. Of the 20,000 known plant species in the United States, 200 have become extinct and 730 are endangered or threatened. About 20% of the known freshwater fishes in the world have become extinct or are seriously threatened.

66. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Biologist Edward O. Wilson has compiled the Hundred Heartbeat Club, which includes species of animals that number fewer than a hundred individuals.

67. Figure 20.14

68. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Several researchers estimate that at the current rate of destruction, over half of all plant and animal species will be gone by the end of the 21st century.

69. The Three Main Causes of the Biodiversity Crisis Habitat Destruction Human alteration of habitat –Poses the single greatest threat to biodiversity throughout the biosphere. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

70. Figure 20.15a

71. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Introduced Species Human introduction of exotic species –Ranks second behind habitat loss. –Can cause rapid extinctions.

72. Figure 20.15b

73. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Overexploitation Overexploitation of wildlife –Is the third major threat to biodiversity.

74. Figure 20.15c

75. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Why Biodiversity Matters Humans rely on biodiversity for –Food, clothing, shelter. –Oxygen, soil fertility, medicinal substances. Endemic species –Are those found nowhere else.

76. Figure 20.16

77. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The loss of diversity –Limits the potential for new discoveries of food and medicine. –Reflects large-scale changes in the biosphere that could have catastrophic consequences.

78. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Conservation Biology Conservation biology –Is a goal-oriented science that seeks to counter the loss of biodiversity.

79. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Biodiversity “Hot Spots” A biodiversity hot spot –Is a relatively small area with an exceptional concentration of species.

80. Figure 20.17

81. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Endemic species –Are often found in hot spots. –Are highly sensitive to habitat degradation.

82. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Some biologists –Estimate that loss of habitat will cause the extinction of about half the species in hot spots.

83. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Conservation at the Population and Species Levels Much of the discussion of the biodiversity crisis centers on species.

84. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The U.S. Endangered Species Act –Defines an endangered species as one that is “in danger of extinction throughout all or a significant portion of its range.” –Defines a threatened species as one likely to become endangered in the foreseeable future.

85. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Habitat Fragmentation and Subdivided Populations Population fragmentation –Is the splitting and consequent isolation of portions of populations by habitat degradation. –Is one of the most harmful effects of habitat loss due to human activities.

86. Figure 20.18

87. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fragmentation usually results in –A decrease in the overall size of populations. –A reduction in gene flow among subpopulations.

88. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Subpopulations –Are separated into habitat patches that vary in quality. A source habitat –Is one of good quality where a subpopulation’s reproductive success exceeds it death rate. –Can produce enough individuals that some disperse to other areas.

89. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings A sink habitat –Is one of poor quality where the subpopulation’s death rate exceeds its reproductive success. Dispersal of individuals to sink habitats because of habitat loss can sometimes threaten the survival of subpopulations in source habitats.

90. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings What Makes a Good Habitat? Identifying the specific combination of habitat factors that is critical for a species is fundamental to conservation biology.

91. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The red-cockaded woodpecker –Provides a case study in identifying critical habitat factors.

92. Figure 20.19a

93. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Certain habitat factors are necessary for these birds: –Mature pines and low growth of plants

94. Figure 20.19b

95. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings A habitat that has become a sink has thick and tall undergrowth.

96. Figure 20.19c

97. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Conserving Species amid Conflicting Demands Conservation biology –Often highlights the relationships between biology and society.

98. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Competing demands for habitat are almost always an issue.

99. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Conservation at the Ecosystem Level Conservation biology –Increasingly aims at sustaining the biodiversity of entire communities and ecosystems. Landscape ecology –Is the application of ecological principles to the study of land-use patterns.

100. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Edges and Corridors Edges between ecosystems –Are prominent features of landscapes. –Can be natural.

101. Figure 20.20a

102. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings –Can be created by humans. –Can have both positive and negative effects on biodiversity.

103. Figure 20.20b

104. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings A movement corridor –Is a narrow strip or series of small clumps of quality habitat connecting otherwise isolated patches.

105. Figure 20.21

106. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Corridors –Can promote dispersal and help sustain populations. –Are especially important to species that migrate between different habitats seasonally.

107. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Zoned Reserves A zoned reserve –Is an extensive region of land that includes one or more areas undisturbed by humans.

108. Figure 20.22a

109. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The areas surrounding zoned reserves –Continue to be used to support the human population, but they are protected from extensive alteration.

110. Figure 20.22b

111. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Goal of Sustainable Development Sustainable development –Balances human needs with the health of the biosphere. The goal of sustainable development –Is the long-term prosperity of human societies and the ecosystems that support them.

112. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Some ways to promote sustainability

113. Table 20.1

114. Evolution Connection: Biophilia and an Environmental Ethic Edward O. Wilson makes the case that biophilia, the human desire to affiliate with other life in its many forms, is innate. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

115. Figure 20.23

116. Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings Most biologists –Have embraced the concept of biophilia. –Have turned their passion for nature into careers.

117. Figure 20.24