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Ecology Part 2: Population Ecology & Community Ecology Ch 53-54 -…
Ecology Part 2: Population Ecology & Community Ecology Ch 53-54
Ch 53: Population Ecology
Population basics
Population
Same species
Same area
Same time
Interbreeding potential
Density
Individuals per unit area
Example: deer per square mile
Example: bacteria per mL
Dispersion
Clumped
Most common
Food/resources grouped
Social behavior
Example: wolf packs
Uniform
Even spacing
Territorial behavior
Competition
Example: nesting seabirds
Random
No pattern
Resources evenly spread
Example: windblown plants
Population size factors
Births
Add individuals
Natality
Deaths
Remove individuals
Mortality
Immigration
Move into population
Increases size
Emigration
Move out of population
Decreases size
Demographics
Demography
Study of population change
Birth rates
Death rates
Age structure
Life tables
Age-specific survival
Death probability
Used to predict population trends
Survivorship curves
Type I
High survival early
Death later in life
Few offspring
High parental care
Example: humans
Type II
Constant death rate
Equal risk at all ages
Example: squirrels
Type III
High death early
Many offspring
Low parental care
Example: oysters
Reproductive tables
Age-specific reproduction
Female offspring per age group
Population growth prediction
Exponential growth
Ideal conditions
Unlimited resources
No predators
No disease
No space limits
J-shaped curve
Slow start
Rapid increase
Growth accelerates
Per capita rate of increase
r
Birth rate minus death rate
Higher r = faster growth
Examples
Bacteria in fresh media
Invasive species
Population after disaster recovery
Logistic growth
Realistic growth model
Resources limited
Space limited
Competition increases
Carrying capacity
K
Maximum population environment supports
Population levels off near K
S-shaped curve
Early exponential growth
Slowing growth
Stable population size
Population near K
Birth rate decreases
Death rate increases
Resource competition stronger
Overshoot
Population passes K
Resource shortage
Population crash possible
Life history traits
Life history
Survival pattern
Reproduction pattern
Age at maturity
Number of offspring
Semelparity
One big reproductive event
Many offspring
Death after reproduction
Example: salmon
Iteroparity
Repeated reproduction
Fewer offspring each time
Longer lifespan
Example: humans
Trade-offs
Energy is limited
Growth vs reproduction
Survival vs offspring number
Parental care vs offspring amount
r-selected traits
Many offspring
Small body size
Early maturity
Little parental care
Unstable environments
Example: insects
K-selected traits
Few offspring
Larger body size
Late maturity
High parental care
Stable environments
Example: elephants
Population regulation
Density-dependent factors
Effect increases with population density
Negative feedback
Controls population near K
Examples
Competition
Predation
Disease
Territoriality
Toxic waste buildup
Density-independent factors
Effect not based on density
Abiotic events
Can reduce any population
Examples
Fire
Storms
Drought
Floods
Freezing temperatures
Competition for resources
Food
Water
Nesting sites
Light
Space
Predator-prey cycles
Prey increases
Predators increase later
Prey decreases
Predators decrease later
Disease
Spreads faster in dense populations
Example: flu in crowded areas
Example: fungal infections in dense plants
Human population growth
Global growth
Rapid increase historically
Slowing in some regions
Still increasing overall
Demographic transition
High birth and death rates
Death rate drops first
Birth rate drops later
Population stabilizes
Age structure
Pre-reproductive
Reproductive
Post-reproductive
Predicts future growth
Ecological footprint
Land and water needed
Resource use
Waste absorption
Varies by country
Ch 54: Community Ecology
Community basics
Community
All populations in area
Multiple species
Species interactions
Species diversity
Species richness
Number of species
More species = higher richness
Relative abundance
How common each species is
Evenness
High diversity
More stable community
More complex interactions
Niche
Species role
Resource use
Habitat
Interactions
Fundamental niche
Full possible niche
No competition
Ideal range
Realized niche
Actual niche used
Limited by competition
Limited by predators
Community interactions
Interspecific competition
/ -
Both species harmed
Shared limited resource
Example: two birds eating same seeds
Competitive exclusion
Two species cannot occupy same niche
One species outcompetes other
Local extinction possible
Resource partitioning
Species divide resources
Reduces competition
Example: different feeding zones
Character displacement
Trait differences increase
Occurs where species overlap
Reduces competition
Predation
/ -
Predator benefits
Prey harmed
Example: wolf eats deer
Prey defenses
Camouflage
Blending in
Avoid detection
Mimicry
Looks like dangerous species
Protection by resemblance
Warning coloration
Bright colors
Signals danger or poison
Chemical defenses
Toxins
Bad taste
Herbivory
/ -
Animal eats plant/algae
Plant harmed
Herbivore benefits
Plant defenses
Thorns
Spines
Chemicals
Tough leaves
Symbiosis
Close long-term interaction
Species live closely together
Parasitism
/ -
Parasite benefits
Host harmed
Example: tapeworm
Mutualism
/ +
Both species benefit
Example: bees and flowers
Commensalism
/ 0
One benefits
Other unaffected
Example: barnacles on whales
Facilitation
/ + or + / 0
Species helps another species
Example: plants giving shade
Trophic structure
Trophic levels
Feeding positions
Energy transfer
Food chain organization
Primary producers
Autotrophs
Photosynthesis
Base of food chain
Example: plants
Primary consumers
Herbivores
Eat producers
Example: grasshoppers
Secondary consumers
Carnivores
Eat herbivores
Example: frogs
Tertiary consumers
Top predators
Eat other carnivores
Example: hawks
Decomposers
Break down dead matter
Recycle nutrients
Example: fungi
Example: bacteria
Food chains
Linear feeding path
Producer to consumers
Simple energy flow
Food webs
Multiple food chains
More realistic
Complex feeding relationships
Energy transfer
Energy lost as heat
Less energy at higher levels
Limits food chain length
Dominant species
Most abundant
Highest biomass
Strong community effect
Keystone species
Big effect despite low abundance
Removal changes community
Example: sea otters
Ecosystem engineers
Physically change habitat
Create resources for others
Example: beavers
Bottom-up control
Nutrients/producers control community
More producers = more consumers
Top-down control
Predators control lower levels
More predators = fewer herbivores
Fewer herbivores = more plants
Trophic cascade
Predator affects multiple levels
Indirect community effects
Disturbance & succession
Disturbance
Event changes community
Removes organisms
Changes resources
Examples
Fire
Storms
Floods
Drought
Human activity
Nonequilibrium model
Communities constantly changing
Disturbance prevents perfect stability
Intermediate disturbance hypothesis
Moderate disturbance
Highest diversity
Too little disturbance = dominant species take over
Too much disturbance = few species survive
Ecological succession
Community change over time
Species replace each other
Primary succession
No soil at start
Bare rock
Pioneer species first
Example: after glacier retreat
Pioneer species
First colonizers
Break down rock
Build soil
Example: lichens
Secondary succession
Soil remains
Faster recovery
Example: after fire
Example: abandoned farm
Climax community
Late-stage community
Relatively stable
Can still be disturbed
Biogeographic factors
Latitude
Tropical areas
High species richness
Warm temperatures
High sunlight
More rainfall
Polar areas
Lower diversity
Colder temperatures
Shorter growing season
Climate
Temperature
Water availability
Sunlight
Seasonality
Species-area relationship
Larger area
More habitats
More species
Lower extinction risk
Island biogeography
Island size
Larger islands
More species
Lower extinction
Distance from mainland
Near islands
More immigration
More species
Equilibrium model
Immigration rate
Extinction rate
Species number balance
Pathogens & communities
Pathogen
Disease-causing organism
Virus
Bacterium
Fungus
Protist
Community effects
Reduces population size
Changes species interactions
Can alter food webs
Zoonotic pathogens
Move from animals to humans
Example: influenza
Example: coronavirus
Disease spread
High density increases spread
Travel increases spread
Climate change can shift ranges
Human impact
Habitat destruction
Wildlife contact
Global movement
New disease outbreaks
Key connections between Ch 53 and Ch 54
Population to community
Population
One species
Size and growth
Density and dispersion
Community
Many species
Interactions
Food webs
Competition link
Population ecology
Limits population size
Density-dependent factor
Community ecology
Shapes niches
Can cause competitive exclusion
Predation link
Population ecology
Causes predator-prey cycles
Regulates population size
Community ecology
Controls trophic levels
Can create trophic cascades
Disturbance link
Population ecology
Can reduce population size
Density-independent factor
Community ecology
Can start succession
Can change diversity
Big test ideas
Population questions
What changes population size?
What limits growth?
What does K mean?
What type of survivorship curve?
Community questions
What type of interaction?
Who benefits or is harmed?
Which species controls the community?
How does disturbance affect diversity?
Ecology Part 2: Population Ecology & Community Ecology Ch 53-54
Ch 53: Population Ecology
Population basics
Population
Same species
Same area
Same time
Interbreeding potential
Density
Individuals per unit area
Example: deer per square mile
Example: bacteria per mL
Dispersion
Clumped
Most common
Food/resources grouped
Social behavior
Example: wolf packs
Uniform
Even spacing
Territorial behavior
Competition
Example: nesting seabirds
Random
No pattern
Resources evenly spread
Example: windblown plants
Population size factors
Births
Add individuals
Natality
Deaths
Remove individuals
Mortality
Immigration
Move into population
Increases size
Emigration
Move out of population
Decreases size
Demographics
Demography
Study of population change
Birth rates
Death rates
Age structure
Life tables
Age-specific survival
Death probability
Used to predict population trends
Survivorship curves
Type I
High survival early
Death later in life
Few offspring
High parental care
Example: humans
Type II
Constant death rate
Equal risk at all ages
Example: squirrels
Type III
High death early
Many offspring
Low parental care
Example: oysters
Reproductive tables
Age-specific reproduction
Female offspring per age group
Population growth prediction
Exponential growth
Ideal conditions
Unlimited resources
No predators
No disease
No space limits
J-shaped curve
Slow start
Rapid increase
Growth accelerates
Per capita rate of increase
r
Birth rate minus death rate
Higher r = faster growth
Examples
Bacteria in fresh media
Invasive species
Population after disaster recovery
Logistic growth
Realistic growth model
Resources limited
Space limited
Competition increases
Carrying capacity
K
Maximum population environment supports
Population levels off near K
S-shaped curve
Early exponential growth
Slowing growth
Stable population size
Population near K
Birth rate decreases
Death rate increases
Resource competition stronger
Overshoot
Population passes K
Resource shortage
Population crash possible
Life history traits
Life history
Survival pattern
Reproduction pattern
Age at maturity
Number of offspring
Semelparity
One big reproductive event
Many offspring
Death after reproduction
Example: salmon
Iteroparity
Repeated reproduction
Fewer offspring each time
Longer lifespan
Example: humans
Trade-offs
Energy is limited
Growth vs reproduction
Survival vs offspring number
Parental care vs offspring amount
r-selected traits
Many offspring
Small body size
Early maturity
Little parental care
Unstable environments
Example: insects
K-selected traits
Few offspring
Larger body size
Late maturity
High parental care
Stable environments
Example: elephants
Population regulation
Density-dependent factors
Effect increases with population density
Negative feedback
Controls population near K
Examples
Competition
Predation
Disease
Territoriality
Toxic waste buildup
Density-independent factors
Effect not based on density
Abiotic events
Can reduce any population
Examples
Fire
Storms
Drought
Floods
Freezing temperatures
Competition for resources
Food
Water
Nesting sites
Light
Space
Predator-prey cycles
Prey increases
Predators increase later
Prey decreases
Predators decrease later
Disease
Spreads faster in dense populations
Example: flu in crowded areas
Example: fungal infections in dense plants
Human population growth
Global growth
Rapid increase historically
Slowing in some regions
Still increasing overall
Demographic transition
High birth and death rates
Death rate drops first
Birth rate drops later
Population stabilizes
Age structure
Pre-reproductive
Reproductive
Post-reproductive
Predicts future growth
Ecological footprint
Land and water needed
Resource use
Waste absorption
Varies by country
Ch 54: Community Ecology
Community basics
Community
All populations in area
Multiple species
Species interactions
Species diversity
Species richness
Number of species
More species = higher richness
Relative abundance
How common each species is
Evenness
High diversity
More stable community
More complex interactions
Niche
Species role
Resource use
Habitat
Interactions
Fundamental niche
Full possible niche
No competition
Ideal range
Realized niche
Actual niche used
Limited by competition
Limited by predators
Community interactions
Interspecific competition
/ -
Both species harmed
Shared limited resource
Example: two birds eating same seeds
Competitive exclusion
Two species cannot occupy same niche
One species outcompetes other
Local extinction possible
Resource partitioning
Species divide resources
Reduces competition
Example: different feeding zones
Character displacement
Trait differences increase
Occurs where species overlap
Reduces competition
Predation
/ -
Predator benefits
Prey harmed
Example: wolf eats deer
Prey defenses
Camouflage
Blending in
Avoid detection
Mimicry
Looks like dangerous species
Protection by resemblance
Warning coloration
Bright colors
Signals danger or poison
Chemical defenses
Toxins
Bad taste
Herbivory
/ -
Animal eats plant/algae
Plant harmed
Herbivore benefits
Plant defenses
Thorns
Spines
Chemicals
Tough leaves
Symbiosis
Close long-term interaction
Species live closely together
Parasitism
/ -
Parasite benefits
Host harmed
Example: tapeworm
Mutualism
/ +
Both species benefit
Example: bees and flowers
Commensalism
/ 0
One benefits
Other unaffected
Example: barnacles on whales
Facilitation
/ + or + / 0
Species helps another species
Example: plants giving shade
Trophic structure
Trophic levels
Feeding positions
Energy transfer
Food chain organization
Primary producers
Autotrophs
Photosynthesis
Base of food chain
Example: plants
Primary consumers
Herbivores
Eat producers
Example: grasshoppers
Secondary consumers
Carnivores
Eat herbivores
Example: frogs
Tertiary consumers
Top predators
Eat other carnivores
Example: hawks
Decomposers
Break down dead matter
Recycle nutrients
Example: fungi
Example: bacteria
Food chains
Linear feeding path
Producer to consumers
Simple energy flow
Food webs
Multiple food chains
More realistic
Complex feeding relationships
Energy transfer
Energy lost as heat
Less energy at higher levels
Limits food chain length
Dominant species
Most abundant
Highest biomass
Strong community effect
Keystone species
Big effect despite low abundance
Removal changes community
Example: sea otters
Ecosystem engineers
Physically change habitat
Create resources for others
Example: beavers
Bottom-up control
Nutrients/producers control community
More producers = more consumers
Top-down control
Predators control lower levels
More predators = fewer herbivores
Fewer herbivores = more plants
Trophic cascade
Predator affects multiple levels
Indirect community effects
Disturbance & succession
Disturbance
Event changes community
Removes organisms
Changes resources
Examples
Fire
Storms
Floods
Drought
Human activity
Nonequilibrium model
Communities constantly changing
Disturbance prevents perfect stability
Intermediate disturbance hypothesis
Moderate disturbance
Highest diversity
Too little disturbance = dominant species take over
Too much disturbance = few species survive
Ecological succession
Community change over time
Species replace each other
Primary succession
No soil at start
Bare rock
Pioneer species first
Example: after glacier retreat
Pioneer species
First colonizers
Break down rock
Build soil
Example: lichens
Secondary succession
Soil remains
Faster recovery
Example: after fire
Example: abandoned farm
Climax community
Late-stage community
Relatively stable
Can still be disturbed
Biogeographic factors
Latitude
Tropical areas
High species richness
Warm temperatures
High sunlight
More rainfall
Polar areas
Lower diversity
Colder temperatures
Shorter growing season
Climate
Temperature
Water availability
Sunlight
Seasonality
Species-area relationship
Larger area
More habitats
More species
Lower extinction risk
Island biogeography
Island size
Larger islands
More species
Lower extinction
Distance from mainland
Near islands
More immigration
More species
Equilibrium model
Immigration rate
Extinction rate
Species number balance
Pathogens & communities
Pathogen
Disease-causing organism
Virus
Bacterium
Fungus
Protist
Community effects
Reduces population size
Changes species interactions
Can alter food webs
Zoonotic pathogens
Move from animals to humans
Example: influenza
Example: coronavirus
Disease spread
High density increases spread
Travel increases spread
Climate change can shift ranges
Human impact
Habitat destruction
Wildlife contact
Global movement
New disease outbreaks
Key connections between Ch 53 and Ch 54
Population to community
Population
One species
Size and growth
Density and dispersion
Community
Many species
Interactions
Food webs
Competition link
Population ecology
Limits population size
Density-dependent factor
Community ecology
Shapes niches
Can cause competitive exclusion
Predation link
Population ecology
Causes predator-prey cycles
Regulates population size
Community ecology
Controls trophic levels
Can create trophic cascades
Disturbance link
Population ecology
Can reduce population size
Density-independent factor
Community ecology
Can start succession
Can change diversity
Big test ideas
Population questions
What changes population size?
What limits growth?
What does K mean?
What type of survivorship curve?
Community questions
What type of interaction?
Who benefits or is harmed?
Which species controls the community?
How does disturbance affect diversity?