1. ENVIRONMENTAL SCIENCE
CHAPTER 4: Biodiversity and Evolution

2. Core Case Study: Why Are Amphibians Vanishing? (1)
Habitat loss and fragmentation
Prolonged drought
Increased ultraviolet radiation
Parasites
Viral and fungal diseases

3. Core Case Study: Why Are Amphibians Vanishing? (2)
Pollution
Climate change
Overhunting
Nonnative predators and competitors
33% of all amphibian species face extinction

4. Fig. 4-1, p. 61

5. 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.

6. Biodiversity (1) Species diversity
A set of individuals that can mate and produce fertile offspring
8-100 million species total; likely million
2 million species identified
~50% in endangered tropical rainforests

7. Biodiversity (2) Genetic diversity Ecosystem diversity
Biomes
Distinct climate
Certain species, especially vegetation
Functional diversity

8. Fig. 4-2, p. 61

9. these types of biodiversity?
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.
Active Figure 4.2: Natural capital: the major components of the earth’s biodiversity—one of the
earth’s most important renewable resources (Concept 4-1). See an animation based on this figure at CengageNOW.
Question: Give two examples of how people, in their daily living, intentionally or unintentionally degrade each of
these types of biodiversity?
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. 61

10. Fig. 4-3, p. 61

11. Fig. 4-4, p. 63

12. Coastal mountain ranges Sierra Nevada Great American Desert Rocky
Average annual precipitation
cm (40-50 in.)
cm (30-40 in.)
50-75 cm (20-30 in.)
25-50 cm (10-20 in.)
below-25 cm (0-10 in.)
Denver
Baltimore
San Francisco
St. Louis
Las Vegas
Coastal mountain
ranges
Sierra Nevada
Great American
Desert
Rocky
Mountains
Great
Plains
Mississippi
River Valley
Appalachian
Mountains
Figure 4.4: Major biomes found along the 39th parallel across the United States. The differences reflect changes in climate, mainly differences in average annual precipitation and temperature.
Coastal chaparral
and scrub
Coniferous forest
Desert
Coniferous forest
Prairie grassland
Deciduous forest
Fig. 4-4, p. 63

13. Science Focus: Insects
Around for ~400 million years
Bad reputation
Useful to humans and ecosystems
Vital roles in sustaining life
Pollinators
Natural pest control
Renewing soils

14. Fig. 4-A, p. 62

15. Fig. 4-A, p. 62

16. 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).

17. Theory of Evolution Fossils
Mineralized and petrified remains
Skeletons, bones, and shells
Leaves and seeds
Impressions in rocks
Fossil record incomplete: ~1% of all species
Charles Darwin, On the Origin of Species, 1859

18. Population Changes over Time
Populations evolve by becoming genetically different over time
Genetic variability – mutations
Random changes in DNA molecules in genes
Can occur spontaneously
External agents: radiation
Can create a heritable trait

19. Natural Selection
Adaptive traits - genetically favorable traits that increase the probability to survive and reproduce
Trait – heritable and lead to differential reproduction
Faced with environmental change
Adapt through evolution
Migrate
Become extinct

20. Evolution through Natural Selection Summarized
Genes mutate, individuals are selected, and populations evolve such that they are better adapted to survive and reproduce under existing environmental conditions.

21. Fig. 4-5, p. 65

22. and eventually (d) replace all or most of the nonresistant bacteria.
A group of bacteria, including genetically resistant ones, are exposed to an antibiotic
Most of the normal bacteria die
The genetically resistant bacteria start multiplying
Eventually the resistant strain
replaces all or most of the strain affected by the antibiotic
Figure 4.5: Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all
individuals except those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply
and eventually (d) replace all or most of the nonresistant bacteria.
Normal bacterium
Resistant bacterium
Fig. 4-5, p. 65

23. and eventually (d) replace all or most of the nonresistant bacteria.
A group of bacteria, including genetically resistant ones, are
exposed to an antibiotic
Normal bacterium
Resistant bacterium
Eventually the resistant strain
replaces the strain affected by
the antibiotic
The genetically resistant bacteria
start multiplying
Most of the normal bacteria die
Figure 4.5: Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all
individuals except those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply
and eventually (d) replace all or most of the nonresistant bacteria.
Stepped Art
Fig. 4-5, p. 83

24. Adaptation through Natural Selection Has Limits
Humans unlikely to evolve and have skin that’s not harmed by UV radiation
Desired trait must already be in the gene pool.
Must have high reproductive capacity so adaptive traits can be spread rapidly

25. Three Myths about Evolution through Natural Selection Refuted
“Survival of the fittest” does not mean “survival of the strongest”
Organisms don’t develop traits just because they would be useful: giraffes and long necks
There is no grand plan of nature to create more perfectly adapted species – no trend toward genetic perfection

26. Science Focus: How Did We Become Such a Powerful Species?
Key adaptations – also enabled us to modify environment
Opposable thumbs
Walk upright
Complex brains
Transmit ideas to others
Develop technologies to alter environment
Technology dominates earth’s life support systems and NPP

27. 4-3 How Do Geological Processes and Climate Changes 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.

28. Plate Tectonics
Locations of continents and oceans determine earth’s climate
Movement of continents allow species to move and adapt
Earthquakes and volcanoes affect biological evolution by separating populations of a species and allowing new species to develop

29. Fig. 4-6, p. 66

30. an area of land splitting apart cause the extinction of a species?
225 million years ago
135 million years ago
65 million years ago
Present
Figure 4.6: Over millions of years, the earth’s continents have moved very slowly on several gigantic tectonic plates.
This process plays a role in the extinction of species, as continental areas split apart, and also in the rise of new
species when isolated island areas such as the Hawaiian Islands and the Galapagos Islands are created. Rock and
fossil evidence indicates that 200–250 million years ago, all of the earth’s present-day continents were connected
in a supercontinent called Pangaea (top). About 180 million years ago, Pangaea began splitting apart as the earth’s
tectonic plates separated, eventually resulting in today’s locations of the continents (bottom). Question: How might
an area of land splitting apart cause the extinction of a species?
Fig. 4-6, p. 66

31. 225 million years ago
135 million years ago
Present
65 million years ago
Figure 4.3: Over millions of years, the earth’s continents have moved very slowly on several gigantic tectonic plates. This process plays a role in the extinction of species as land areas split apart and also in the rise of new species when once isolated land areas combine. Rock and fossil evidence indicates that 200–250 million years ago all of the earth’s present-day continents were locked together in a supercontinent called Pangaea (top left). About 180 million years ago, Pangaea began splitting apart as the earth’s huge plates separated, and their movements eventually resulted in the present-day locations of the continents (bottom right).
Question: How might an area of land splitting apart cause the extinction of a species?
Stepped Art
Fig. 4-6, p. 66

32. Earth’s Long-Term Climate Changes
Cooling and warming periods – affect evolution and extinction of species
Change ocean levels and area
Glaciers expanding and contracting
Climate changes
Opportunities for the evolution of new species
Many species go extinct

33. Fig. 4-7, p. 67

34. Northern Hemisphere Ice coverage Legend
18,000
years before
present
Northern Hemisphere
Ice coverage
Modern day
(August)
Legend
Continental ice
Sea ice
Land above sea level
Figure 4.7: Changes in ice coverage in the northern hemisphere during the past 18,000 years.
(Data from the National Oceanic and Atmospheric Administration)
Fig. 4-7, p. 67

35. Science Focus: Earth is Just Right for Life to Thrive
Life needs a temperature range that results in liquid water
Earth’s orbit: right distance from sun
Earth’s optimal gravity: keeps atmosphere
Favorable temperature range over earth history has promoted evolution and biodiversity
Favorable oxygen level in atmosphere

36. 4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity?
Concept 4-4 Human activities decrease the earth’s biodiversity by causing the premature extinction of species and by destroying or degrading habitats needed for the development of new species.

37. Speciation Speciation Geographic isolation Reproductive isolation
One species splits into two or more species that can no longer breed and produce fertile offspring
Geographic isolation
Reproductive isolation

38. Fig. 4-8, p. 68

39. Arctic Fox Northern population Early fox population Gray Fox Southern
Adapted to cold
through heavier fur, short ears, short legs, and short nose. White fur matches snow for camouflage.
Arctic Fox
Northern
population
Spreads northward
and southward
and separates
Early fox
population
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Gray Fox
Adapted to heat through lightweight
fur and long ears, legs, and nose, which
give off more heat.
Southern
population
Figure 4.8: Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation.
Fig. 4-8, p. 68

40. Science Focus: Changing Genetic Traits
Artificial selection
Selective breeding: crossbreeding varieties within same species to enhance desired traits
Grains, fruits, vegetables, dogs, other animals
Genetic engineering
Add, delete, or alter DNA segments
Add desirable genes from other species
New drugs, pest-resistant plants
Controversial

41. Extinction (1) Biological extinction Local extinction
Entire species gone
Local extinction
All members of a species in a specific area gone
Endemic species vulnerable to extinction
Background extinction
Speciation generally more rapid than extinction

42. Extinction (2) Mass extinction
Earth took millions of years to recover from previous mass extinctions
Balance between speciation and extinction determines biodiversity of earth
Humans cause premature extinction of species

43. Human Activities and Extinction
Cause premature extinction of species

44. 4-5 What Is Species Diversity and Why Is It Important?
Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of some ecosystems.

45. Species Diversity Species richness Species evenness
Varies with geographic location
Species richness declines towards poles

46. Richness and Sustainability
Hypothesis
Does a community with high species richness have greater sustainability and productivity?
Research suggests “yes”

47. 4-6 What Roles Do Species Play in an Ecosystem?
Concept 4-6 Each species plays a specific ecological role called its niche.

48. Ecological Niche (1)
Species occupy unique niches and play specific roles in an ecosystem
Includes everything required for survival and reproduction
Water
Sunlight
Space
Temperatures
Food requirements

49. Ecological Niche (2) Generalist species Specialist species
Native species
Nonnative species
Spread in new, suitable niches

50. Fig. 4-10, p. 72

51. competition and allows sharing of limited resources.
Ruddy turnstone searches under shells and pebbles
for small invertebrates
Herring gull
is a tireless
scavenger
Brown pelican dives for fish, which it locates from the air
Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds
Dowitcher probes
deeply into mud in
search of snails,
marine worms, and
small crustaceans
Black skimmer
seizes small fish
at water surface
Flamingo feeds on
minute organisms
in mud
Figure 4.10: Specialized feeding niches of various bird species in a coastal wetland. This specialization reduces
competition and allows sharing of limited resources.
Louisiana heron
wades into water
to seize small fish
Oystercatcher feeds on
clams, mussels, and other
shellfish into which it
pries its narrow beak
Piping plover feeds on insects and tiny crustaceans on sandy beaches
Scaup and other diving
ducks feed on mollusks,
crustaceans, and aquatic
vegetation
Knot (sandpiper)
picks up worms
and small crustaceans
left by receding tide
Fig. 4-10, p. 72

52. Science Focus: Cockroaches
Existed for 350 million years – 3,500 known species
Highly adapted, rapidly producing generalists
Consume almost anything
Endure food shortage
Survive everywhere except polar regions
Avoid predation
Carry human diseases

53. Fig. 4-11, p. 72

54. Indicator Species Early warning system Fish Birds Butterflies
Amphibians

55. Fig. 4-12, p. 74

56. predators and competitors.
Adult frog
(3 years)
Young frog
Tadpole
develops
into frog
Sperm
Sexual
reproduction
Tadpole
Figure 4.12: Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful environmental factors at different points in
their life cycle. Such environmental factors include habitat loss, drought, pollution, increased UV radiation, parasitism, disease, overhunting for food (frog legs), and nonnative
predators and competitors.
Eggs
Fertilized egg
development
Egg hatches
Organ formation
Fig. 4-12, p. 74

57. Keystone Species
Significant role in their food web: large affect on types and abundances of other species in an ecosystem
Elimination may alter structure and/or function of ecosystem
Pollinators
Top predators

58. Foundation Species Create habitats and ecosystems Beavers Elephants
Seed dispersers

59. Science Focus: American Alligator
Highly adaptable
Only natural predator is humans
1967 – endangered species list
Successful environmental comeback
Keystone species

60. Case Study: Why Should We Protect Sharks?
Remove injured, sick animals
Many are gentle giants
Provide potential insight into cures for human diseases such as cancer
Keystone species
Hunted and killed by humans

61. Three Big Ideas from This Chapter - #1
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).

62. Three Big Ideas from This Chapter - #2
Human activities are decreasing the earth’s vital biodiversity by causing the premature extinction of species and by disrupting habitats needed for the development of new species.

63. Three Big Ideas from This Chapter - #3
Each species plays a specific ecological role in the ecosystem where it is found (ecological niche).

64. Animation: Carbon Bonds

65. Animation: Stanley Miller’s Experiment

66. Animation: Evolutionary Tree of Life

67. Animation: Stabilizing Selection

68. Animation: Disruptive Selection

69. Animation: Moth Populations

70. Animation: Adaptive Trait

71. Animation: Speciation on an Archipelago

72. Animation: Evolutionary Tree Diagrams

73. Animation: Gause’s Competition Experiment

74. Animation: Species Diversity By Latitude

75. Animation: Humans Affect Biodiversity

76. Animation: Habitat Loss and Fragmentation

77. Animation: Transferring Genes into Plants

78. Video: Ancient Human Skull
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79. Video: Asteroid Menace
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80. Video: Bachelor Pad at the Zoo
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81. Video: Cloned Pooch
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82. Video: Creation vs. Evolution
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83. Video: Dinosaur Discovery
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84. Video: Glow-in-the-Dark Pigs
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85. Video: Hsing Hsing Dies
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86. Video: Mule Clones
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87. Video: New Species Found
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88. Video: Penguin Rescue
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