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MILLER/SPOOLMAN
LIVING IN THE ENVIRONMENT
17TH
Chapter 5
Biodiversity, Species
Interactions, and Population
Control
How Wolves Change Rivers
• Summarize the effects of the reintroduction of
wolves to Yellowstone National Park.
• Be specific:
• What changes have been seen with regards to plants,
animals, and physical landscape?
• What type of species is the wolf?
• Chapter 4
• Summarize this series of events on an index card.
• Use specific, detailed language.
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.
Principle of Competitive Exclusion
• No two species can occupy the same ecological niche
for long.
• The species that is more efficient in using available
resources will exclude the other.
• The other species disappears or develops a new niche,
exploiting resources differently.
• Resource Partitioning
Species Interact in Five Major Ways
• Interspecific Competition
• Members of two or more species interact to gain access to the same
limited resources, such as food water, light, and space.
• Predation
• A member of one species (the predator) feeds directly on all or part of
a member of another species (the prey).
• Parasitism
• One organism (the parasite) feeds on another organism, usually by
living on or in the host.
• Mutualism
• An interaction that benefits both species by providing each with food,
shelter, or some other resource.
• Commensalism
• An interaction that benefits one species but has little of no effect on the
other.
With a partner …
• Come up with two examples of each type of species
interaction.
• Write them down to share.
Resource Partitioning Among Warblers
Fig. 5-2, p. 106
Most Consumer Species Feed on Live
Organisms of Other Species (2)
• Prey may avoid capture by
1. Run, swim, fly
2. Protection: shells, bark, thorns
3. Camouflage
4. Chemical warfare
5. Warning coloration
6. Mimicry
7. Deceptive looks
8. Deceptive behavior
Camouflage
(a) Span worm
Fig. 5-5a, p. 109
Camouflage
(b) Wandering leaf insect
Fig. 5-5b, p. 109
Chemical warfare
(c) Bombardier beetle
Fig. 5-5c, p. 109
Chemical Warfare+Warning Coloration
(d) monarch butterfly
Fig. 5-5d, p. 109
Chemical Warfare+Warning Coloration
(e) Poison dart frog
Fig. 5-5e, p. 109
Biomimicry
(f) Viceroy butterfly
Fig. 5-5f, p. 109
Deceptive looks
(g) Io moth
Fig. 5-5g, p. 109
Deceptive behavior: When
touched, snake caterpillar
changes shape to look like
head of snake.
(h) Snake caterpillar
Fig. 5-5h, p. 109
Biomimicry
• The Indonesian Mimic Octopus
Do all predators kill their prey?
Explain.
Predator and Prey Interactions Can
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
Coevolution: A Langohrfledermaus
Bat Hunting a Moth
Fig. 5-6, p. 110
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
Parasitism: Trout with Blood-Sucking Sea Lamprey
Fig. 5-7, p. 110
In Some Interactions, Both Species
Benefit
• Mutualism
• Nutrition and protection relationship
• Gut inhabitant mutualism
• Not cooperation: it’s mutual exploitation
Mutualism: Hummingbird and Flower
Fig. 5-8, p. 110
Mutualism: Oxpeckers Clean Rhinoceros; Anemones
Protect and Feed Clownfish
Fig. 5-9, p. 111
In Some Interactions, One Species Benefits
and the Other Is Not Harmed
• Commensalism
• Epiphytes
• Birds nesting in trees
Commensalism: Bromiliad Roots on Tree Trunk Without
Harming Tree
Fig. 5-10, p. 111
Catching up on HW …
• #2, p. 122
• Another one to do now: #3 p. 123
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.
Science Focus: Threats to Kelp Forests
• Kelp forests: biologically diverse marine habitat
• Major threats to kelp forests
1. Sea urchins
2. Pollution from water
run-off
3. Global warming
• Kelp Forest Facts (NOAA)
Purple Sea Urchin
Fig. 5-A, p. 108
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
Population Size of Southern Sea Otters
Off the Coast of Southern California
Fig. 5-B, p. 114
Most Populations Live Together in
Clumps or Patches (1)
• Population: group of interbreeding individuals of the
same species
• Population distribution
1. Clumping
2. Uniform dispersion
3. Random dispersion
Most Populations Live Together in
Clumps or Patches (2)
• Why clumping?
1. Species tend to cluster where resources are
available
2. Groups have a better chance of finding clumped
resources
3. Protects some animals from predators
4. Packs allow some to get prey
Generalized Dispersion Patterns
Fig. 5-12, p. 112
Populations Can Grow, Shrink, or
Remain Stable (1)
• Population size governed by
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Births
Deaths
Immigration
Emigration
• Population change =
(births + immigration) – (deaths + emigration)
Populations Can Grow, Shrink, or
Remain Stable (2)
• Age structure
• Pre-reproductive age
• Reproductive age
• Post-reproductive age
Factors That Can Limit Population Size
• Range of tolerance
• Variations in physical and chemical environment
• Limiting factor principle (Index Card)
• 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.
Trout Tolerance of Temperature
Fig. 5-13, p. 113
For humans, what is an example of a
range of tolerance for a physical
environmental factor?
No Population Can Grow Indefinitely:
J-Curves and S-Curves (1)
• Size of populations controlled by limiting factors.
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Precipitation
Soil nutrients
Light
Space
Temperature
Dissolved oxygen content (aquatic systems)
Salinity—amounts of salts dissolved in water (aquatic
systems)
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
indefinitely.
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
Logistic Growth of Sheep in Tasmania
Fig. 5-15, p. 115
Questions
• Is the carrying capacity of an area for a given species
fixed? Why or why not?
• What is the carrying capacity of the earth for
humans?
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Have we reached it?
Will we ever?
What could lead to an increased carrying capacity?
Decreased?
Thomas Malthus, 1766-1834
• Humans need certain resources (e.g., air, food, water, and
shelter). A sustainable habitat is one in which supply of and
demand for these resources are balanced.
• The problem is the difference in growth patterns between the
human population and food production.
• The human population tends to grow exponentially
• The food supply will only grow linearly.
• In this model, humans are bound to outgrow the Earth's
resources.
• Many have argued that Malthus was wrong because he did
not take into account human technology, but even that is
being called into question by some.
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
• Why the population explosion?
Population Graphs: White-Tailed Deer
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
Species Have Different
Reproductive Patterns (1)
• Some species (such as?):
• Many, usually small, offspring
• Little or no parental care
• Massive deaths of offspring
Species Have Different
Reproductive Patterns (2)
• Other species (such as?):
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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
r-selected and K-selected species
Under Some Circumstances Population
Density Affects Population Size
• Density-dependent population controls
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Predation
Parasitism
Infectious disease
Competition for resources
Are modern humans exempt from
nature’s population controls?
Humans Are Not Exempt from
Nature’s Population Controls
• Ireland
• Potato crop in 1845
• Bubonic plague
• Fourteenth century
• AIDS
• Global epidemic
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.
Communities and Ecosystems Change over
Time: Ecological Succession
• Natural ecological restoration
• Primary succession
• Secondary succession
• Video: What’s the difference?
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
• Example of what would lead to primary succession?
Primary Ecological Succession
Fig. 5-19, p. 119
Primary Ecological Succession
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
Natural Ecological Restoration of Disturbed Land
Fig. 5-20, p. 120
Secondary Succession
Secondary Ecological Succession in Yellowstone Following
the 1998 Fire
Fig. 5-21, p. 120
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
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Fires
Hurricanes
Clear-cutting of forests
Plowing of grasslands
Invasion by nonnative species
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
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
Krakatau
• How high did the ash, rock and magma rise during the
volcanic eruption at Krakatau? What about the sulfates and
dust? How would the local and global impacts from these
different sorts of particles have differed?
• How did most species colonize Krakatau in the first months
following the eruption? Give examples of three species that
tend to be early colonizers.
• How did larger species reach the island after the volcano
erupted (reptiles, amphibians, mammals, large insects)?
Describe four means of transport for larger species.
Krakatau, cont.
• Describe the pattern of plant colonization on Rakata. How do
Rakata’s forests differ from other Indonesian island forests
today?
• Describe an example from the text that shows inertia
(persistence) in nature. Then describe an example that shows
resilience.
Three Big Ideas
1. Certain interactions among species affect their use
of resources and their population sizes.
2. There are always limits to population growth in
nature.
3. Changes in environmental conditions cause
communities and ecosystems to gradually alter
their species composition and population sizes
(ecological succession).