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

2. Southern Sea Otter

3. Core Case Study: Southern Sea Otters: Are They Back from the Brink of Extinction?
Habitat
Hunted: early 1900s
Partial recovery by the late 2007

4. Why care about them?

5. Why care about sea otters?
Ethics
Keystone species (Eat sea Urchins)
Tourism dollars

6. Science Focus: Why Should We Care about Kelp Forests?
Kelp forests: one of the most biologically diverse marine habitat
One blade of kelp can grow 2 feet in a single day
Major threats to kelp forests
Sea urchins
Pollution from water run-off
Global warming (changing of the water’s temp)

7. Purple Sea Urchin

8. Video: Kelp forest (Channel Islands)

9. Video: Coral spawning

10. 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.

11. Species Interact in Five Major Ways
Interspecific Competition: over same resources
Predation
Parasitism:
one gains, one loses (not always death)
Mutualism: both gain
Commensalism: one gains, the other gets no benefits

12. Interspecific Competition

13. Most Species Compete with One Another for Certain Resources
Competition for same limited resources (food, shelter, space)
Competitive exclusion principle: no 2 species can occupy exactly the same ecological niche for very long

14. 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

15. Most Consumer Species Feed on Live Organisms of Other Species (2)
Prey may avoid capture by
Camouflage
Chemical warfare
Warning coloration
Mimicry
Deceptive looks
Deceptive behavior

16. Some Ways Prey Species Avoid Their Predators
(a) Span worm
(b) Wandering leaf insect
Some Ways Prey Species Avoid Their Predators
(c) Bombardier beetle
(d) Foul-tasting monarch butterfly
(e) Poison dart frog
(f) Viceroy butterfly mimics
monarch butterfly
Figure 5.2
Some ways in which prey species 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.
(h) When touched,
snake caterpillar changes
shape to look like head of snake.
Stepped Art
Fig. 5-2, p. 103

17. Video: Salmon swimming upstream

18. Predator and Prey Species Can Drive Each Other’s Evolution
Intense natural selection pressures between predator and prey populations
Coevolution

19. Coevolution: A Langohrfledermaus Bat Hunting a Moth

20. Predation

21. Video: Otter feeding

22. Some Species Feed off Other Species by Living on or in Them
Parasitism
Parasite-host interaction may lead to coevolution
Host’s point of view: parasites bad
Population level POV: promote biodiversity, keep populations in check

23. Parasitism: Tree with Parasitic Mistletoe, Trout with Blood-Sucking Sea Lampreys

24. Parasitism
Ticks

25. In Some Interactions, Both Species Benefit
Mutualism
Nutrition and protection relationship
Gut inhabitant mutualism: vast armies of bacteria, break down food
How is a Cow like a termite?
Cooperation between species?

26. Mutualism

27. Mutualism: Oxpeckers Clean Rhinoceros; Anemones Protect and Feed Clownfish

28. Centipede

29. In Some Interactions, One Species Benefits and the Other Is Not Harmed
Commensalism
Epiphytes
Birds nesting in trees
Army ants and silverfish

30. Commensalism: Bromiliad Roots on Tree Trunk Without Harming Tree

31. Chapter 5, section 1
Q1: What are the 5 different ways that species interact with each other? Give an example of each. Describe what is unique about each interaction type.
Q2: Describe a trait possessed by the southern sea otter that helps it a) catch prey and b) avoid being preyed upon
Q3: Compare Competitive exclusion principle with coevolution

32. Q5: Why would detritus feeders and decomposers not considered predators?
Q6: What methods/ways help predators catch their prey?
Q7: What ways have the prey developed to avoid being caught?
Q9: Why can coevolution be described like an arms race?
Q10: Explain how each of the species interactions can affect the population sizes of species in ecosystems.

33. 5-2 How Can Natural Selection Reduce Competition between Species?
Concept 5-2 Some species develop adaptations that allow them to reduce or avoid competition with other species for resources.

34. Question
Do species want to compete for niche space?

35. Some Species Evolve Ways to Share Resources
Resource partitioning
Reduce niche overlap, increase species diversity
Use shared resources at different
Times
Places
Ways

36. Competing Species Can Evolve to Reduce Niche Overlap

37. Sharing the Wealth: Resource Partitioning
Blackburnian Warbler
Black-throated Green Warbler
Cape May Warbler
Bay-breasted Warbler
Yellow-rumped Warbler
Figure 5.8
Sharing the wealth: resource partitioning of five species of insect-eating warblers in the spruce forests of the U.S. state of Maine. Each species minimizes competition for food with the others by spending at least half its feeding time in a distinct portion (shaded areas) of the spruce trees, and by consuming different insect species. (After R. H. MacArthur, “Population Ecology of Some Warblers in Northeastern Coniferous Forests,” Ecology 36 (1958): 533–536.)
Stepped Art
Fig. 5-8, p. 107

38. Insect and nectar eaters
Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Specialist Species of Honeycreepers
Amakihi
Kona Grosbeak
Crested Honeycreeper
Akiapolaau
Figure 5.9
Specialist species of honeycreepers. Evolutionary divergence of honeycreepers into species with specialized ecological niches has reduced competition between these species. Each species has evolved a beak specialized to take advantage of certain types of food resources.
Maui Parrotbill
Apapane
Unkown finch ancestor
Fig. 5-9, p. 108

39. Honey creepers on Hawaii
Evolved into different species, each concentrating on different food resources
Evolutionary divergence-speciation

40. Chapter 5, section 2 questions
Q11: How does resource partitioning increase species diversity? Q12: How did the warblers reduce competition when eating insects on spruce trees? Q13: How is the evolutionary progress of honey creepers an example of evolutionary divergence?

41. Question
How many humans can live on the Earth?
How many cockroaches?

42. 5-3 What Limits the Growth of Populations?
Concept 5-3 No population can continue to grow indefinitely due to:
limitations on resources
competition among species for those resources.

43. What information can be used to describe the differences between 2 different populations of the same creature?

44. Populations Have Certain Characteristics (1)
Populations differ in
Distribution
Numbers
Age structure
These values are Population dynamics

45. Populations Characteristics can change
due to:
Temperature change
Presence of disease, organisms or harmful chemicals
Resource availability
Arrival or disappearance of competing species

46. Population distributions

47. Most Populations Live Together in Clumps or Patches (1)
Different types of population distribution:
Clumping
Uniform dispersion (what would cause this?)
Random dispersion (what would cause this?)

48. 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
Herds protect some animals from predators
Packs allow some predators to get prey
Temporary groups for mating and caring for young

49. Why does the population of the US continues to increase, despite the birthrate falling below 2.0 kids per mother?

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

51. Populations Can Grow, Shrink, or Remain Stable (2)
Age structure
Pre-reproductive age
Reproductive age (if greatest %, greatest growth)
Post-reproductive age
Excluding emigration/immigration, a population that has an even distribution amongst the groups will remain stable.

52. How would you describe the US population, in terms of age?
Pre-reproductive
Reproductive
Post-reproductive

53. Population Growth Rates
Biotic potential: capacity for pop growth
Low (elephants, whales)
High (insects and bacteria)
Intrinsic rate of increase (r)
Steepness of curve
Individuals in populations with high r
Reproduce early in life
Have short generation times (adaptable)
Can reproduce many times
Have many offspring each time they reproduce

54. Better than roaches and bunnies
A species of bacteria could carpet the entire surface of the earth 1 foot deep in 36 hours, if there was nothing to control its population numbers.
What stops it from doing so?

55. Environmental resistance
Combo of all factors which limit growth
Size of populations limited by
Light
Water
Space
Nutrients
Exposure to too many competitors, predators or infectious diseases

56. No Population Can Grow Indefinitely: J-Curves and S-Curves (3)
Carrying capacity (K)
Max population sustained indefinitely
Exponential growth (j-curve)
(even 1-2% growth is exponential)
Logistic growth (s-curve)
Rapid growth followed by leveling off

57. The first part of any population graph should be a J
As population nears carrying capacity, graph should change into an s-curve

58. No Population Can Continue to Increase in Size Indefinitely

59. Logistic Growth of a Sheep Population on the island of Tasmania, 1800–1925

60. When a Population Exceeds Its Habitat’s Carrying Capacity, Its Population Can Crash
Carrying capacity: not fixed, dependent on environmental factors (food, conditions)
Reproductive time lag may lead to overshoot
Dieback (crash)
Overshoot Damage may reduce area’s carrying capacity

61. Science Focus: Why Are Protected Sea Otters Making a Slow Comeback?
Low biotic potential
Prey for orcas
Cat parasites (from kitty liter flushed)
Thorny-headed worms (seabirds)
Toxic algae blooms (urea, fertilizer)
PCBs and other toxins
Oil spills

62. 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.)

63. Exponential Growth, Overshoot, and Population Crash of a Reindeer

64. Story of the Reindeer 26 introduced to island in Bering Sea
No predators, pop soared
Food is slow growth lichens and mosses
Pop starved, crashed to 8 in 1950

65. Species Have Different Reproductive Patterns
r-Selected species, opportunists
Capacity for high rate of pop increase
Little or no care of offspring
Large populations
K-selected species, competitors
Reproduce later in life
Long life spans
Small number of offspring, care
Small Populations

66. Positions of r- and K-Selected Species on the S-Shaped Population Growth Curve

67. Genetic Diversity Can Affect the size, success of Small Populations
Founder effect: few individuals start new colony
Demographic bottleneck: few individuals survive catastrophe
Genetic drift: random changes to gene frequencies in pop that lead to unequal reproductive success
Inbreeding: increase of defective genes in small pop
Use above to estimate minimum viable population size

68. Population Density and Population Size
Density independent pop controls
Mostly abiotic like weather, forest fires…
Density-dependent population controls
Predation
Parasitism
Infectious disease
Competition for resources

69. Several Different Types of Population Change Occur in Nature
Stable
Irruptive:
external conditions (temp…)
Cyclic fluctuations, boom-and-bust cycles (more than once, internal)
Top-down population regulation (bunnies-lynx)
Bottom-up population regulation (lemmings)
Irregular (no drastic increases)

70. Population Cycles for the Snowshoe Hare and Canada Lynx (notice general delay in lynx crashes)

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

72. Questions on 5.3 Q15: Why do populations tend to live in clumps?
Q17: What are the 3 age group categories in a population’s age structure
Q21: Which group grasshoppers or elephants have a high biotic potential? Why?
Q25: Use the concepts of carrying capacity to explain why there are always limits to population growth in nature
Q30: Distinguish between r-selected species and k-selected species and give an example of each type. Which are humans?

73. White-tailed deer

74. 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
Results of current population explosion for deer
Lyme disease
Deer-vehicle accidents
Eating garden plants and shrubs
Ways to control the deer population

75. Solutions to the consequences of the exploding deer population
List at least 3 different solutions that would result in a sustainable deer population. (several in textbook or come up with your own
For each solution, describe:
The economic and environmental cost
Changes in the population dynamics over time
Main causes for change in the carrying capacity for deer

76. Modeling population growth lab
Vernier

78. 5-4 How Do Communities and Ecosystems Respond to Changing Environmental Conditions?
Concept 5-4 The structure and species composition of communities and ecosystems change in response to changing environmental conditions through a process called ecological succession.

79. Mt. St. Helens-Secondary Succession

80. Primary Succession Candidate

81. Candidates for primary succession

82. Communities and Ecosystems Change over Time: Ecological Succession
Natural ecological restoration
Primary succession
Starts from bare rock
Secondary succession
Does not start from bare rock
New home construction (why?)

83. Some Ecosystems Start from Scratch: Primary Succession
No soil in a terrestrial system
No bottom sediment in an aquatic system
Early successional plant species, pioneer
Midsuccessional plant species
Late successional plant species

84. Primary Ecological Succession
Figure 5.16
Primary ecological succession. Over almost a thousand years, 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. 5-16, p. 116

86. 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

87. Natural Ecological Restoration of Disturbed Land (secondary)
Figure 5.17
Natural ecological restoration of disturbed land. 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. Questions: Do you think the annual weeds (left) would continue to thrive in the mature forest (right)? Why or why not? See an animation based on this figure at CengageNOW.
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. 5-17, p. 117

88. 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

89. Factors that affect the rate of succession
Facilitation:
one set of species makes area makes area suitable for following species, less for themselves (mosses/lichens and grasses)
Inhibition:
hinder establishment and growth of species ex: pine trees
Tolerance:
unaffected by plants in earlier stages (mature trees vs shade plants)

90. Succession Doesn’t Follow a Predictable Path
Traditional view
Balance of nature and a climax community
Achieves equilibrium
Current view
Succession Doesn’t follow a predictable path
Ever-changing mosaic of patches of vegetation
Mature late-successional ecosystems
State of continual disturbance and change, not permanent equilibrium

91. 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
Tipping point

92. Tropical Rain Forest
Ecosystem is persistent but is not resilant

93. Arthropod biodiversity lab

94. UN project Questions
Give 2 examples of r-selected and k-selected species that live in your country
Obtain a picture of a park or wilderness area of your country. Where in terms of ecological succession (early, mid, late, climax) does your picture represent? State evidence to support your choice
Indicate specific examples from your country for the following, (avoid examples that could show up globally):
a) Interspecific competition
b) Predator and Prey
c) Parasite and host
d) Mutualism
e) Commensalism
f) For each example given describe the population distribution pattern