1. Figure 4.1
The American alligator plays an important ecological role in its marsh and swamp habitats in the southeastern United States. Since being classified as an endangered species in 1967, it has recovered enough to have its status changed from endangered to threatened—an outstanding success story in wildlife conservation.
Fig. 4-1, p. 77

2. Figure 4.2
Natural capital: the major components of the earth’s biodiversity—one of the earth’s most important renewable resources. See an animation based on this figure at CengageNOW™. Question: What are three examples of how people, in their daily living, intentionally or unintentionally degrade each of these types of biodiversity?
Fig. 4-2, p. 79

3. Figure 4.3
Overview of the evolution of life on the earth into six major kingdoms of species as a result of natural selection. For more details, see p. S46 in Supplement 7.
Fig. 4-3, p. 81

4. Prokaryotes
Eukaryotes
Eubacteria
Archaebacteria
Protists
Plants
Fungi
Animals
Cenozoic
First humans
Mesozoic
Extinction of dinosaurs
Paleozoic
Plants
colonize land
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
Figure 4.3
Overview of the evolution of life on the earth into six major kingdoms of species as a result of natural selection. For more details, see p. S46 in Supplement 7.
3,000
3,500
Oldest prokaryotic
fossils
4,000
Earth cool enough
for crust to solidify
Origin of Earth
4,500
Fig. 4-3, p. 81

5. Figure 4.4
Fossilized skeleton of an herbivore that lived during the Cenozoic era from 26–66 million years ago.
Fig. 4-4, p. 82

6. Figure 4.5
Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all but those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace the nonresistant bacteria.
Fig. 4-5, p. 83

7. 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
Figure 4.5
Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all but those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace the nonresistant bacteria.
Normal bacterium
Resistant bacterium
Fig. 4-5, p. 83

8. 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 but those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace the nonresistant bacteria.
Stepped Art
Fig. 4-5, p. 83

9. 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 land areas split apart, and also in the rise of new species when 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 tectonic plates separated, eventually resulting in today’s locations of the continents (bottom right). Question: How might an area of land splitting apart cause the extinction of a species?
Fig. 4-6, p. 85

10. 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 land areas split apart, and also in the rise of new species when 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 tectonic plates separated, eventually resulting in today’s locations of the continents (bottom right). Question: How might an area of land splitting apart cause the extinction of a species?
Fig. 4-6, p. 85

11. 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 land areas split apart, and also in the rise of new species when 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 tectonic plates separated, eventually resulting in today’s 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. 85

12. Figure 4.7
Changes in ice coverage in the northern hemisphere during the past 18,000 years. Question: What are two characteristics of an animal and two characteristics of a plant that natural selection would have favored as these ice sheets (left) advanced? (Data from the National Oceanic and Atmospheric Administration)
Fig. 4-7, p. 85

13. Northern Hemisphere Ice coverage
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. Question: What are two characteristics of an animal and two characteristics of a plant that natural selection would have favored as these ice sheets (left) advanced? (Data from the National Oceanic and Atmospheric Administration)
Fig. 4-7, p. 85

14. Figure 4.8
Geographic isolation can lead to reproductive isolation, divergence of gene pools, and speciation.
Fig. 4-8, p. 87

15. Arctic Fox Northern population Gray Fox Southern population
Adapted to cold
through heavier fur,
short ears, short legs,
and short nose. White
fur matches snow for
camouflage.
Northern
population
Spreads north
and south
and separates
Different environmental
conditions lead to different
selective pressures and evolution
into two different species.
Early fox
population
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. 87

16. Figure 4.9
Male golden toad in Costa Rica’s high-altitude Monteverde Cloud Forest Reserve. This species has recently become extinct, primarily because changes in climate dried up its habitat.
Fig. 4-9, p. 87

17. Figure 4.A
An example of genetic engineering. The 6-month-old mouse on the left is normal; the same-age mouse on the right has a human growth hormone gene inserted in its cells. Mice with the human growth hormone gene grow two to three times faster and twice as large as mice without the gene. Question: How do you think the creation of such species might change the process of evolution by natural selection?
Fig. 4-A, p. 88

18. Figure 4.10
Variations in species richness and species evenness. A coral reef (left), with a large number of different species (high species richness), generally has only a few members of each species (low species evenness). In contrast, a grove of aspen trees in Alberta, Canada, in the fall (right) has a small number of different species (low species richness), but large numbers of individuals of each species (high species evenness).
Fig. 4-10a, p. 89

19. Figure 4.10
Variations in species richness and species evenness. A coral reef (left), with a large number of different species (high species richness), generally has only a few members of each species (low species evenness). In contrast, a grove of aspen trees in Alberta, Canada, in the fall (right) has a small number of different species (low species richness), but large numbers of individuals of each species (high species evenness).
Fig. 4-10b, p. 89

20. Figure 4.11
Specialist species such as the giant panda have a narrow niche (left) and generalist species such as a raccoon have a broad niche (right).
Fig. 4-11, p. 91

21. Niche separation Niche breadth
Specialist species
with a narrow niche
Generalist species
with a broad niche
Niche
separation
Number of individuals
Figure 4.11
Specialist species such as the giant panda have a narrow niche (left) and generalist species such as a raccoon have a broad niche (right).
Niche
breadth
Region of
niche overlap
Resource use
Fig. 4-11, p. 91

22. Figure 4.12
As generalists, cockroaches are among the earth’s most adaptable and prolific species. This is a photo of an American cockroach.
Fig. 4-12, p. 92

23. Figure 4.13
Specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources.
Fig. 4-13, p. 93

24. surface water in search of small crustaceans, insects, and seeds
Ruddy turnstone
searches under
shells and pebbles
for small
invertebrates
Dowitcher probes
deeply into mud in
search of snails,
marine worms, and
small crustaceans
Black skimmer
seizes small fish
at water surface
Brown pelican dives
for fish, which it
locates from the air
Herring gull
is a tireless
scavenger
Avocet sweeps bill
through mud and
surface water in search
of small crustaceans,
insects, and seeds
Flamingo feeds on minute organisms in mud
Figure 4.13
Specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources.
Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation
Louisiana heron wades into water to seize small fish
Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak
Knot (sandpiper)
picks up worms
and small crustaceans
left by receding tide
Piping plover feeds on insects and tiny
crustaceans on sandy beaches
Fig. 4-13, p. 93

25. Figure 4.14
Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful factors at different points in their life cycle. Such factors include habitat loss, drought, pollution, increased ultraviolet radiation, parasitism, disease, overhunting by humans, and nonnative predators and competitors.
Fig. 4-14, p. 94

26. Adult frog (3 years) Tadpole develops into frog
Young frog
Sperm
Tadpole develops
into frog
Sexual
reproduction
Tadpole
Figure 4.14
Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful factors at different points in their life cycle. Such factors include habitat loss, drought, pollution, increased ultraviolet radiation, parasitism, disease, overhunting by humans, and nonnative predators and competitors.
Eggs
Fertilized egg
development
Egg hatches
Organ formation
Fig. 4-14, p. 94