1. Chapter 5 Biodiversity, Species Interactions, and Population Control

2. Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction?
Habitat
Hunted: early 1900s
Partial recovery
Why care about sea otters?
Ethics
Tourism dollars
Keystone species

3. Southern Sea Otter
Figure 5.1: An endangered southern sea otter in Monterey Bay, California (USA), uses a stone to crack the shell of a clam (left). It lives in a giant kelp bed (right). Scientific studies indicate that the otters act as a keystone species in a kelp forest system by helping to control the populations of sea urchins and other kelp-eating species.
Fig. 5-1a, p. 104

4. 5-1 How Do Species Interact?
Concept 5-1 Five types of species interactions—competition, predation, parasitism, mutualism, and commensalism—affect the resource use and population sizes of the species in an ecosystem.

5. Species Interact in Five Major Ways
Interspecific Competition – occurs when members of 2 or more species interact to gain access to the same limited resources
Predation – when one species eats another
Parasitism - when one organism feeds on another by living on them
Mutualism – an interaction benefits both species
Commensalism – One species benefits the other is unaffected.
pg 105

6. Most Species Compete with One Another for Certain Resources
For limited resources like food light and space
Ecological niche for exploiting resources
Some niches overlap – the greater the overlap the more competition
If one species is more successful the others, the others have to move, adapt by shifting feeding habits or behavior, suffer population decline, become extinct

7. Some Species Evolve Ways to Share Resources
Resource partitioning
Using only parts of resource – different parts of the tree or shore.
Using at different times
Using in different ways – eating different species of insects.

8. Resource Partitioning Among Warblers
Figure 5.2: Sharing the wealth: This diagram illustrates resource partitioning among five species of insect-eating warblers in the spruce forests of the U.S. state of Maine. Each species minimizes competition with the others for food by spending at least half its feeding time in a distinct portion (yellow highlighted areas) of the spruce trees, and by consuming somewhat different insect species. (After R. H. MacArthur, “Population Ecology of Some Warblers in Northeastern Coniferous Forests,” Ecology 36 (1958): 533–536.)
Fig. 5-2, p. 106

9. Specialist Species of Honeycreepers
This is called adaptive radiation.
Figure 5.3: Specialist species of honeycreepers: Through natural selection, different species of honeycreepers developed specialized ecological niches that reduced competition between these species. Each species has evolved a specialized beak to take advantage of certain types of food resources.
Fig. 5-3, p. 107

10. Most Consumer Species Feed on Live Organisms of Other Species (1)
Predators may capture prey by
Walking
Swimming
Flying
Pursuit and ambush
Camouflage
Chemical warfare
Types
Herbivores
Omnivores
Insectivores
Carnivores

11. Predator-Prey Relationships
Figure 5.4: Predator-prey relationship: This brown bear (the predator) in the U.S. state of Alaska has captured and will feed on this salmon (the prey).
Fig. 5-4, p. 107

12. Most Consumer Species Feed on Live Organisms of Other Species (2)
Prey may avoid capture by
Run, swim, fly – with highly developed senses.
Protection: shells, bark, thorns
Camouflage
Chemical warfare
Warning coloration – often black and yellow stripes
Mimicry
Deceptive looks
Deceptive behavior
If it is small and strikingly beautiful it is probably poisonous.
If it is strikingly beautiful and easy to catch it is probably deadly. E.O. Wilson

13. Some Ways Prey Species Avoid Their Predators
Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
Fig. 5-5, p. 109

14. Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(a) Span worm
Fig. 5-5a, p. 109

15. (b) Wandering leaf insect
Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(b) Wandering leaf insect
Fig. 5-5b, p. 109

16. Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(c) Bombardier beetle
Fig. 5-5c, p. 109

17. (d) Foul-tasting monarch butterfly
Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(d) Foul-tasting monarch butterfly
Fig. 5-5d, p. 109

18. Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(e) Poison dart frog
Fig. 5-5e, p. 109

19. (f) Viceroy butterfly mimics monarch butterfly
Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(f) Viceroy butterfly mimics monarch butterfly
Fig. 5-5f, p. 109

20. (g) Hind wings of Io moth resemble eyes of a much larger animal.
Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(g) Hind wings of Io moth resemble eyes of a much larger animal.
Fig. 5-5g, p. 109

21. Figure 5.5: These prey species have developed specialized ways to avoid their predators: (a, b) camouflage, (c–e) chemical warfare, (d, e) warning coloration, (f) mimicry, (g) deceptive looks, and (h) deceptive behavior.
(h) When touched, snake caterpillar changes shape to look like head of snake.
Fig. 5-5h, p. 109

22. Science Focus: Threats to Kelp Forests
Kelp forests: biologically diverse marine habitat
Major threats to kelp forests
Sea urchins
Pollution from water run-off
Global warming – warming oceans

23. Purple Sea Urchin
Figure 5.A: This purple sea urchin inhabits the coastal waters of the U.S. state of California.
Fig. 5-A, p. 108

24. Predator and Prey Interactions Can and Do Drive Each Other’s Evolution
Intense natural selection pressures between predator and prey populations
Coevolution
Interact over a long period of time
Bats and moths: echolocation of bats and sensitive hearing of moths

25. Coevolution: A Langohrfledermaus Bat Hunting a Moth
Fig. 5-6, p. 110

26. Some Species Feed off Other Species by Living on or in Them
Parasitism
Parasite is usually much smaller than the host
Parasite rarely kills the host
Parasite-host interaction may lead to coevolution

27. Parasitism: Trout with Blood-Sucking Sea Lamprey
Fig. 5-7, p. 110

28. In Some Interactions, Both Species Benefit
Mutualism
Nutrition and protection relationship
Gut inhabitant mutualism – micro-organisms in cows and termites stomachs.
Not cooperation: it’s mutual exploitation

29. Mutualism: Hummingbird and Flower
Figure 5.8: Mutualism: This hummingbird benefits by feeding on nectar in this flower, and it benefits the flower by pollinating it.
Fig. 5-8, p. 110

30. Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish
Fig. 5-9, p. 111

31. In Some Interactions, One Species Benefits and the Other Is Not Harmed
Commensalism
Epiphytes – plants that grow on other plants (air plants)
Birds nesting in trees

32. Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree
Figure 5.10: In an example of commensalism, this bromeliad—an epiphyte, or air plant—in Brazil’s Atlantic tropical rain forest roots on the trunk of a tree, rather than in soil, without penetrating or harming the tree. In this interaction, the epiphyte gains access to sunlight, water, and nutrients from the tree’s debris; the tree apparently remains unharmed and gains no benefit.
Fig. 5-10, p. 111

33. 5-2 What Limits the Growth of Populations?
Concept 5-2 No population can continue to grow indefinitely because of limitations on resources and because of competition among species for those resources.

34. Most Populations Live Together in Clumps or Patches (1)
Population: group of interbreeding individuals of the same species
Population distribution - 3 types
Clumping
Uniform dispersion
Random dispersion

35. Most Populations Live Together in Clumps or Patches (2)
Why clumping?
Species tend to cluster where resources are available
Groups have a better chance of finding clumped resources
Protects some animals from predators
Packs allow some to get prey

36. Population of Snow Geese
Figure 5.11: This large group of birds is a population, or flock, of snow geese.
Fig. 5-11, p. 112

37. Generalized Dispersion Patterns
Figure 5.12: This diagram illustrates three general dispersion patterns for populations. Clumps (a) are the most common dispersion pattern, mostly because resources such as grass and water are usually found in patches. Where such resources are scarce, uniform dispersion (b) is more common. Where they are plentiful, a random dispersion (c) is more likely. Question: Why do you think elephants live in clumps or groups?
Fig. 5-12, p. 112

38. (a) Clumped (elephants)
Figure 5.12: This diagram illustrates three general dispersion patterns for populations. Clumps (a) are the most common dispersion pattern, mostly because resources such as grass and water are usually found in patches. Where such resources are scarce, uniform dispersion (b) is more common. Where they are plentiful, a random dispersion (c) is more likely. Question: Why do you think elephants live in clumps or groups?
(a) Clumped (elephants)
Fig. 5-12a, p. 112

39. (b) Uniform (creosote bush)
Figure 5.12: This diagram illustrates three general dispersion patterns for populations. Clumps (a) are the most common dispersion pattern, mostly because resources such as grass and water are usually found in patches. Where such resources are scarce, uniform dispersion (b) is more common. Where they are plentiful, a random dispersion (c) is more likely. Question: Why do you think elephants live in clumps or groups?
(b) Uniform (creosote bush)
Fig. 5-12b, p. 112

40. (c) Random (dandelions)
Figure 5.12: This diagram illustrates three general dispersion patterns for populations. Clumps (a) are the most common dispersion pattern, mostly because resources such as grass and water are usually found in patches. Where such resources are scarce, uniform dispersion (b) is more common. Where they are plentiful, a random dispersion (c) is more likely. Question: Why do you think elephants live in clumps or groups?
(c) Random (dandelions)
Fig. 5-12c, p. 112

41. Populations Can Grow, Shrink, or Remain Stable (1)
Population size governed by
Births
Deaths
Immigration
Emigration
Population change =
(births + immigration) – (deaths + emigration)

42. Populations Can Grow, Shrink, or Remain Stable (2)
Age structure – distribution of individuals of various age groups
Pre-reproductive age
Reproductive age
Post-reproductive age

43. Some Factors Can Limit Population Size
Range of tolerance
Variations in physical and chemical environment that the organism can live with.
Limiting factor principle
Too much or too little of any physical or chemical factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance
Precipitation
Nutrients
Sunlight, etc

44. Trout Tolerance of Temperature
Figure 5.13: This diagram illustrates the range of tolerance for a population of organisms, such as trout, to a physical environmental factor—in this case, water temperature. Range of tolerance restrictions prevent particular species from taking over an ecosystem by keeping their population size in check. Question: For humans, what is an example of a range of tolerance for a physical environmental factor?
Fig. 5-13, p. 113

45. No Population Can Grow Indefinitely: J-Curves and S-Curves (1)
Size of populations controlled by limiting factors:
Light
Water
Space
Nutrients
Exposure to too many competitors, predators or infectious diseases

46. No Population Can Grow Indefinitely: J-Curves and S-Curves (2)
Environmental resistance
All factors that act to limit the growth of a population
Carrying capacity (K)
Maximum population a given habitat can sustain

47. No Population Can Grow Indefinitely: J-Curves and S-Curves (3)
Exponential growth
Starts slowly, then accelerates to carrying capacity when meets environmental resistance
Logistic growth
Decreased population growth rate as population size reaches carrying capacity

48. Logistic Growth of Sheep in Tasmania
Figure 5.15: This graph tracks the logistic growth of a sheep population on the island of Tasmania between 1800 and After sheep were introduced in 1800, their population grew exponentially, thanks to an ample food supply and few predators. By 1855, they had overshot the land’s carrying capacity. Their numbers then stabilized and fluctuated around a carrying capacity of about 1.6 million sheep.
Fig. 5-15, p. 115

49. Science Focus: Why Do California’s Sea Otters Face an Uncertain Future?
Low biotic potential
Prey for orcas
Cat parasites
Thorny-headed worms
Toxic algae blooms
PCBs and other toxins
Oil spills

50. Population Size of Southern Sea Otters Off the Coast of So
Population Size of Southern Sea Otters Off the Coast of So. California (U.S.)
Figure 5.B: This graph tracks the population size of southern sea otters off the coast of the U.S. state of California, 1983–2009. According to the U.S. Geological Survey, the California southern sea otter population would have to reach at least 3,090 animals for 3 years in a row before it could be considered for removal from the endangered species list. (Data from U.S. Geological Survey)
Fig. 5-B, p. 114

51. Case Study: Exploding White-Tailed Deer Population in the U.S.
1900: deer habitat destruction and uncontrolled hunting
1920s–1930s: laws to protect the deer
Current population explosion for deer
Spread Lyme disease
Deer-vehicle accidents
Eating garden plants and shrubs
Ways to control the deer population
Suburbs, hunting, lack of predators, deer contraceptives
What do you think the solution is?

52. Mature Male White-Tailed Deer
Figure 5.16: This is a mature male (buck) white-tailed deer.
Fig. 5-16, p. 115

53. When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash
A population exceeds the area’s carrying capacity
Reproductive time lag may lead to overshoot
Population crash
Damage may reduce area’s carrying capacity

54. Exponential Growth, Overshoot, and Population Crash of a Reindeer
Figure 5.17: This graph tracks the exponential growth, overshoot, and population crash of reindeer introduced onto the small Bering Sea island of St. Paul. When 26 reindeer (24 of them female) were introduced in 1910, lichens, mosses, and other food sources were plentiful. By 1935, the herd size had soared to 2,000, overshooting the island’s carrying capacity. This led to a population crash, when the herd size plummeted to only 8 reindeer by Question: Why do you think the sizes of some populations level off while others such as the reindeer in this example exceed their carrying capacities and crash?
Fig. 5-17, p. 116

55. Species Have Different Reproductive Patterns (1)
Some species
Many, usually small, offspring
Little or no parental care
Massive deaths of offspring
Insects, bacteria, algae

56. Species Have Different Reproductive Patterns (2)
Other species
Reproduce later in life
Small number of offspring with long life spans
Young offspring grow inside mother
Long time to maturity
Protected by parents, and potentially groups
Humans
Elephants

57. Under Some Circumstances Population Density Affects Population Size
Population density = # of individual of a species in an area or volume.
Density-dependent population controls – increase as population increases.
Predation
Parasitism
Infectious disease
Competition for resources

58. Several Different Types of Population Change Occur in Nature
Stable
Irruptive
Population surge, followed by crash
Cyclic fluctuations, boom-and-bust cycles
Top-down population regulation
Bottom-up population regulation
Irregular

59. Population Cycles for the Snowshoe Hare and Canada Lynx
Figure 5.18: This graph represents the population cycles for the snowshoe hare and the Canadian lynx. At one time, scientists believed these curves provided evidence that these predator and prey populations regulated one another. More recent research suggests that the periodic swings in the hare population are caused by a combination of top-down population control—through predation by lynx and other predators—and bottom-up population control, in which changes in the availability of the food supply for hares help to determine their population size, which in turn helps to determine the lynx population size. (Data from D. A. MacLulich)
Fig. 5-18, p. 118

60. Population size (thousands)
160
Hare
Lynx
140
120
100 80
Population size (thousands) 60 40 20
Figure 5.18: This graph represents the population cycles for the snowshoe hare and the Canadian lynx. At one time, scientists believed these curves provided evidence that these predator and prey populations regulated one another. More recent research suggests that the periodic swings in the hare population are caused by a combination of top-down population control—through predation by lynx and other predators—and bottom-up population control, in which changes in the availability of the food supply for hares help to determine their population size, which in turn helps to determine the lynx population size. (Data from D. A. MacLulich)
1845
1855
1865
1875
1885
1895
1905
1915
1925
1935
Year
Fig. 5-18, p. 118

61. Humans Are Not Exempt from Nature’s Population Controls
Ireland
Potato crop in 1845
Bubonic plague
Fourteenth century
AIDS
Global epidemic

62. 5-3 How Do Communities and Ecosystems Respond to Changing Environmental Conditions?
Concept 5-3 The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession.

63. Communities and Ecosystems Change over Time: Ecological Succession
Natural ecological restoration
Primary succession
Secondary succession

64. Some Ecosystems Start from Scratch: Primary Succession
No soil in a terrestrial system
No bottom sediment in an aquatic system
Takes hundreds to thousands of years
Need to build up soils/sediments to provide necessary nutrients

65. Primary Ecological Succession
Figure 5.19: Primary ecological succession: Over almost a thousand years, these plant communities developed, starting on bare rock exposed by a retreating glacier on Isle Royal, Michigan (USA) in northern Lake Superior. The details of this process vary from one site to another. Question: What are two ways in which lichens, mosses, and plants might get started growing on bare rock?
Fig. 5-19, p. 119

66. Balsam fir, paper birch, and white spruce forest community
Figure 5.19: Primary ecological succession: Over almost a thousand years, these plant communities developed, starting on bare rock exposed by a retreating glacier on Isle Royal, Michigan (USA) in northern Lake Superior. The details of this process vary from one site to another. Question: What are two ways in which lichens, mosses, and plants might get started growing on bare rock?
Balsam fir, paper birch, and white spruce forest community
Jack pine, black spruce, and aspen
Heath mat
Small herbs and shrubs
Lichens and mosses
Exposed rocks
Time
Fig. 5-19, p. 119

67. paper birch, and white spruce forest community Jack pine,
Balsam fir,
paper birch, and white spruce forest community
Jack pine,
black spruce,
and aspen
Heath mat
Small herbs
and shrubs
Lichens and
mosses
Exposed
rocks
Time
Stepped Art
Fig. 5-19, p. 119

68. Some Ecosystems Do Not Have to Start from Scratch: Secondary Succession (1)
Some soil remains in a terrestrial system
Some bottom sediment remains in an aquatic system
Ecosystem has been
Disturbed
Removed
Destroyed

69. Natural Ecological Restoration of Disturbed Land
Figure 5.20: Natural ecological restoration of disturbed land: This diagram shows the undisturbed secondary ecological succession of plant communities on an abandoned farm field in the U.S. state of North Carolina. It took 150–200 years after the farmland was abandoned for the area to become covered with a mature oak and hickory forest. A new disturbance such as deforestation or fire would create conditions favoring pioneer species such as annual weeds. In the absence of new disturbances, secondary succession would recur over time, but not necessarily in the same sequence shown here. See an animation based on this figure at CengageNOW. Questions: Do you think the annual weeds (left) would continue to thrive in the mature forest (right)? Why or why not?
Fig. 5-20, p. 120

70. Mature oak and hickory forest
Figure 5.20: Natural ecological restoration of disturbed land: This diagram shows the undisturbed secondary ecological succession of plant communities on an abandoned farm field in the U.S. state of North Carolina. It took 150–200 years after the farmland was abandoned for the area to become covered with a mature oak and hickory forest. A new disturbance such as deforestation or fire would create conditions favoring pioneer species such as annual weeds. In the absence of new disturbances, secondary succession would recur over time, but not necessarily in the same sequence shown here. See an animation based on this figure at CengageNOW. Questions: Do you think the annual weeds (left) would continue to thrive in the mature forest (right)? Why or why not?
Mature oak and hickory forest
Young pine forest with developing understory of oak and hickory trees
Shrubs and small pine seedlings
Perennial weeds and grasses
Annual weeds
Time
Fig. 5-20, p. 120

71. Secondary Ecological Succession in Yellowstone Following the 1998 Fire
Figure 5.21: These young lodgepole pines growing around standing dead trees after a 1998 forest fire in Yellowstone National Park are an example of secondary ecological succession.
Fig. 5-21, p. 120

72. Some Ecosystems Do Not Have to Start from Scratch: Secondary Succession (2)
Primary and secondary succession
Tend to increase biodiversity
Increase species richness and interactions among species
Primary and secondary succession can be interrupted by
Fires
Hurricanes
Clear-cutting of forests
Plowing of grasslands
Invasion by nonnative species

73. Science Focus: How Do Species Replace One Another in Ecological Succession?
Facilitation
Inhibition
Tolerance

74. Succession Doesn’t Follow a Predictable Path
Traditional view
Balance of nature and a climax community
Current view
Ever-changing mosaic of patches of vegetation
Mature late-successional ecosystems
State of continual disturbance and change

75. Living Systems Are Sustained through Constant Change
Inertia, persistence
Ability of a living system to survive moderate disturbances
Resilience
Ability of a living system to be restored through secondary succession after a moderate disturbance
Some systems have one property, but not the other: tropical rainforests

76. Three Big Ideas
Certain interactions among species affect their use of resources and their population sizes.
There are always limits to population growth in nature.
Changes in environmental conditions cause communities and ecosystems to gradually alter their species composition and population sizes (ecological succession).