Transcript Chapter 5 notes - Aurora City Schools

LIVING IN THE ENVIRONMENT, 18e
G. TYLER MILLER • SCOTT E. SPOOLMAN
5Biodiversity, Species
Interactions, and Population
Control
© Cengage
Cengage Learning
Learning 2015
2015
©
Core Case Study: Southern Sea Otters - A
Species in Recovery
• Live in giant kelp forests
• By the early 1900s they had been hunted
almost to extinction
• Partial recovery since 1977
• Why care about sea otters?
– Ethics
– Tourism dollars
– Keystone species
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Southern Sea Otter
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Fig. 5-1, p. 102
5-1 How Do Species Interact?
• Five types of species interactions—
competition, predation, parasitism,
mutualism, and commensalism—affect the
resource use and population sizes of the
species in an ecosystem
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Most Species Compete with One Another
for Certain Resources
• Five basic types of species interactions
– Interspecific Competition
– Predation
– Parasitism
– Mutualism
– Commensalism
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• Interspecific competition
– Most common interaction
– Members of two or more species compete to
use the same limited resources
– Niches overlap
– Involves one species becoming more efficient
than the other
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Some Species Evolve Ways to Share
Resources
• Resource partitioning
– Populations of some species develop
adaptations that allow them to reduce or avoid
competition with other species for resources.
– Competing species evolve specialized traits
so that they may use only parts of resource
• At different times
• In different ways
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Sharing the Wealth
Blackburnian
Warbler
Black-throated
Green Warbler
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Cape May
Warbler
Bay-breasted
Warbler
Yellow-rumped
Warbler
Stepped Art
Fig. 5-2, p. 103
Specialist Species
of Honeycreepers
Fruit and seed eaters
Insect and nectar eaters
Greater Koa-finch
Kuai Akialaoa
Amakihi
Kona Grosbeak
Akiapolaau
Crested
Honeycreeper
Maui Parrotbill
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Unkown finch ancestor
Apapane
Fig. 5-3, p. 104
Consumer Species Feed on Other Species
• Predation
– A member of one species (predator) feed
directly on all or part of a living organism
(prey) as part of a food web.
– Predator methods:
• Herbivores-walk, swim, or fly to plants they feed on
• Carnivores-pursuit and ambush
• Camouflage
• Chemical warfare
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Consumer Species Feed on Other Species
(cont’d.)
• Prey can avoid predation
– Swim, run, fly fast
– Highly developed senses
– Protective shells, thick bark, or spines
– Camouflage
– Chemical warfare
– Warning coloration
– Mimicry
– Behavioral strategies
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Predator-Prey Relationships
Fig. 5-4, p. 104
Predator-Prey Relationships
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Fig. 5-6, p. 106
Interactions between Predator and Prey
Species
• Intense natural selection pressures
between predator and prey populations
• Coevolution
– Interact over a long period of time
– Changes in the gene pool of one species can
cause changes in the gene pool of the other
– Bats and moths
• Echolocation of bats and sensitive hearing of
moths
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Coevolution
Fig. 5-7, p. 107
Some Species Feed off Other Species by
Living on or inside Them
• Parasitism
– One species (the parasite) feeds on another
organism (the host) by living on or inside the
host
– Parasite is usually much smaller than the host
– Parasite rarely kills the host
– Parasite-host interaction may lead to
coevolution
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Parasitism
Fig. 5-8, p. 107
In Some Interactions, Both Species Benefit
• Mutualism
– Two species benefit
– Nutrition and protective relationship
– Gut inhabitant mutualism
– Not cooperation – mutual exploitation
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Mutualism
Fig. 5-9, p. 108
In Some Interactions, One Species
Benefits and the Other Is Not Harmed
• Commensalism
– Benefits one species and has little affect on
the other
– Epiphytes
– Birds nesting in trees
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Commensalism
Fig. 5-10, p. 108
5-2 Responding to Changing
Environmental Conditions
• How do communities and ecosystems
respond to changing environmental
conditions?
– The structure and species composition of
communities and ecosystems change in
response to changing environmental
conditions through a process called ecological
succession
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Communities and Ecosystems Change
over Time: Ecological Succession
• Ecological succession
– Gradual change in species composition
– Primary succession
• Gradual establishment of a community in a lifeless
areas (no soil in terrestrial ecosystem and no
bottom sediment in an aquatic ecosystem)
– Secondary succession
• Areas of environmental disturbance, but some soil
or bottom sediment remains
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• Both types of success are examples of natural
ecological restoration
– Increase the biodiversity of communities and
ecosystems by increasing species richness
and interactions among species.
– Factors that affect how and rate of
succession:
• 1. facilitation
• 2. inhibition
• 3. tolerance
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Primary Ecological Succession
Exposed
rocks
Lichens
and
mosses
Small herbs
and shrubs
Heath mat
Jack pine,
black spruce,
and aspen
Balsam fir,
paper birch,
and white
spruce forest
community
Fig. 5-11, p. 109
Natural Ecological Restoration
Annual
weeds
Perennial
weeds
and
grasses
Shrubs and
small pine
seedlings
Young pine forest
with developing
understory of oak
and hickory trees
Mature oak and
hickory forest
Fig. 5-12, p. 110
Ecological Succession Does Not Follow a
Predictable Path
• Traditional view
– Succession proceeds in an orderly sequence
along an expected path until a climax
community is reached; balance of nature
• Current view
– Ever-changing mosaic of patches of
vegetation in different stages of succession
– In a state of continual disturbance and
change.
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Living Systems Are Sustained through
Constant Change
• Two aspects of stability or sustainability in
living systems:
• 1. Inertia, or persistence
– Ability of a living system to survive moderate
disturbances
• 2. Resilience
– Ability of a living system to be restored
through secondary succession after a
moderate disturbance
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What Limits the Growth of Populations
• No population can grow indefinitely
because of limitations on resources and
because of competition among species for
those resources
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Most Populations Live in Clumps
• Population
– Group of interbreeding individuals of the same
species
• Population distribution
– Clumped
– Uniform
– Random
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– Clumping
• Most live in clumps. Why?
• 1. Species cluster for resources
• 2. Protection from predators
• 3. Ability to hunt in packs
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A School of Anthias Fish
Fig. 5-13, p. 111
Populations Can Grow, Shrink, or Remain
Stable
• Population size governed by:
– Births and deaths; immigration and emigration
• Population change = (births + immigration)
– (deaths + emigration)
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• Age structure– age group distributions can have a strong
effect on how rapidly populations grow or
decline
– Pre-reproductive age
– Reproductive age
– Post-reproductive age
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Some Factors Can Limit Population Size
• Range of tolerance
– Tolerance to variations in physical and
chemical environment
– Individuals may have different tolerance
ranges because of their genetic makeup,
health, and age.
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Some Factors Can Limit Population Size
• Limiting factors:
– Factors that determine number of organisms
in a population.
– Regulate population growth
• 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
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• Populations density
– Can be a limiting factor
– Number of individuals in a given area
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Trout Tolerance of Temperature
Lower limit
of tolerance
Few
organisms
Abundance of organisms
Few
organisms
No
organisms
Zone of
physiological
stress
Zone of
intolerance
Population size
No
organisms
Higher limit
of tolerance
Zone of
intolerance
Zone of
physiological
stress
Low
Optimum range
Temperature
High
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Fig. 5-13, p. 113
Different Species Have Different
Reproductive Patterns
• To ensure long-term survival of species:
• Some species:
– Have many small offspring
– Little parental involvement
– Algae, bacteria, and most insects
• Other species:
– Reproduce later in life
– Have small number of offspring
– mammals
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No Population Can Grow Indefinitely:
J-Curves and S-Curves
• There are always limits to population
growth in nature
– Environmental resistance:
• combination of all factors that limit population
growth
• Determines the:
– Carrying capacity:
• Maximum population of a given species that a
particular habitat can sustain indefinitely
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No Population Can Grow Indefinitely:
J-Curves and S-Curves (cont’d.)
• Exponential growth
– At a fixed percentage per year
– J-shaped growth curve
– Unlimited resources
• Logistic growth
– Exponential growth that faces environmental
resistance
– Population size stabilizes at carrying capacity
– S-shaped growth curve
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Growth of a Sheep Population
Population overshoots
carrying capacity
Environmental resistance
Number of sheep (millions)
2.0
Carrying capacity
1.5
Population recovers
and stabilizes
1.0
Exponential
growth
Population runs out of
resources and crashes
.5
1800
1825
1850
1875
Year
1900
1925
Fig. 5-16, p. 115
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 deer population explosion
– Spread Lyme disease
– Deer-vehicle accidents
– Eating garden plants and shrubs
• How can we control the deer population?
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White-Tailed Deer Populations
Fig. 5-17, p. 115
When a Population Exceeds Its Carrying
Capacity It Can Crash
• If a population uses up resources and
exceeds the area’s carrying capacity, the
reproductive time lag may lead to
overshoot:
– Subsequent population crash or dieback
– Damage may reduce area’s carrying capacity
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Population Crash
Population
overshoots
carrying
capacity
Number of reindeer
2,000
1,500
Population
crashes
1,000
500
Carrying
capacity
0
1910
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1920
1930
1940
1950
Year
Fig. 5-18, p. 116
Humans Are Not Exempt from Nature’s
Population Controls
• Ireland
– Potato crop in 1845
• Bubonic plague
– Fourteenth century
• AIDS
– Current global epidemic
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Three Big Ideas
• Certain interactions among species
– Affect their use of resources and their
population sizes
• Changes in environmental conditions
– Cause communities and ecosystems to
gradually alter their species composition and
population sizes (ecological succession)
• There are always limits to population
growth in nature
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Tying It All Together – Southern Sea Otters
and Sustainability
• Before European settlers in the U.S., the
sea otter ecosystem was complex
• Settlers began hunting otters
– Disturbed the balance of the ecosystem
• Populations depend on solar energy and
nutrient cycling
– When these are disrupted biodiversity is
threatened
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