How populations grow 3 important characteristics of a
population are -
How populations grow 3 important characteristics of a
population are – Geographic distribution -
How populations grow 3 important characteristics of a
population are – Geographic distribution – describes the
area inhabited by a population
How populations grow 3 important characteristics of a
population are – Population density -
How populations grow 3 important characteristics of a
population are – Population density – number of
individuals per unit area
How populations grow 3 important characteristics of a
population are – Population density – number of
individuals per unit area• Example of low density -
How populations grow 3 important characteristics of a
population are – Population density – number of
individuals per unit area• Example of low density –• Example of high density -
How populations grow 3 important characteristics of a
population are – Growth rate -
How populations grow 3 important characteristics of a
population are – Growth rate – the speed at which a
population may change in numbers
How populations grow Three factors that can affect
population size
How populations grow Three factors that can affect
population size The number of births
How populations grow Three factors that can affect
population size The number of births The number of deaths
How populations grow Three factors that can affect
population size The number of births The number of deaths The number of individuals that enter or
leave a population
How populations grow Immigration -
How populations grow Immigration – the movement of
individuals into an area
How populations grow Immigration – the movement of
individuals into an area Example -
How populations grow Immigration – the movement of
individuals into an area Example – animals in search of mates
or food arrive from outside the population
How populations grow Emigration -
How populations grow Emigration – the movement of
individuals out of a population
How populations grow Emigration – the movement of
individuals out of a population Example -
How populations grow Emigration – the movement of
individuals out of a population Example – young animals approach
maturity and leave area to establish new territories
How populations grow Exponential growth -
How populations grow Exponential growth – occurs when
the individuals in a population reproduce at a constant rate
Exponential growth A graph of exponential growth would
be
Exponential growth A graph of exponential growth would
be J-shaped
Exponential growth A graph of exponential growth would
be J-shaped Example -
Exponential growth A graph of exponential growth would
be J-shaped Example - bacteria
Exponential growth A graph of exponential growth would
be J-shaped Example – bacteria
• Usually occurs
Exponential growth A graph of exponential growth would
be J-shaped Example – bacteria
• Usually occurs under ideal conditions with
Exponential growth A graph of exponential growth would
be J-shaped Example – bacteria
• Usually occurs under ideal conditions with unlimited resources
Exponential growth Bacteria - some are able to
reproduce every 20 minutes
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be __
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be 4
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be 4• Another 20 minutes there will be ___
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be 4• Another 20 minutes there will be 8• In another hour there will be ___
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be 4• Another 20 minutes there will be 8• In another hour there will be 64• In 2 more hours there will be ___
Exponential growth Bacteria - some are able to
reproduce every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be 4• Another 20 minutes there will be 8• In another hour there will be 64• In 2 more hours there will be 512• In just one day there will be ___
Exponential growth Bacteria - some are able to reproduce
every 20 minutes If you begin with one bacteria
• 20 minutes later there will be 2• Another 20 minutes there will be 4• Another 20 minutes there will be 8• In another hour there will be 64• In 2 more hours there will be 512• In just one day there will be
4,720,000,000,000,000,000,000
How population grow Logistic growth -
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth Why might this happen?
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth Why might this happen?
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth Why might this happen?
• Birthrate decreases
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth Why might this happen?
• Birthrate decreases• Deathrate increases
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth Why might this happen?
• Birthrate decreases• Deathrate increases• Or both events occur at same time
How population grow Logistic growth – occurs when a
population’s growth slows or stops following a period of exponential growth Why might this happen?
• Birthrate decreases• Deathrate increases• Or both events occur at same time
Logistic growth
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Graph would be
“S-shaped”
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Graph would be
“S-shaped” Initial growth
would be ___
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Graph would be
“S-shaped” Initial growth
would be slow, followed by a period of ___
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Graph would be
“S-shaped” Initial growth
would be slow, followed by a period of rapid growth
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Graph would be
“S-shaped” Initial growth
would be slow, followed by a period of rapid growth
Growth then___Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Graph would be
“S-shaped” Initial growth
would be slow, followed by a period of rapid growth
Growth then levels off
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Caused by some
sort of __________________ on the
population.
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Caused by some
sort of limitingfactor on the
population.
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Carrying capacity -
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Carrying capacity -
the largest number of individuals that a given environment can support
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Carrying capacity -
What if conditions
change?
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Carrying capacity -
What if conditions
change? The carrying
capacity will also change
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Carrying capacity -
Where is carrying
capacity on “S” shaped curve?
Time (hours)
Num
ber o
f yeast ce
lls
Logistic growth Carrying capacity -
Where is carrying
capacity on “S” shaped curve?
Time (hours)
Num
ber o
f yeast ce
lls
Carrying capacity
Limits on growth Limiting factors -
Limits on growth Limiting factors – a factor that
causes population growth to decrease
Limits on growth Limiting factors – a factor that
causes population growth to decrease Examples -
Limits on growth Limiting factors – a factor that
causes population growth to decrease Examples –
• competition
Limits on growth Limiting factors – a factor that
causes population growth to decrease Examples –
• Competition• predation
Limits on growth Limiting factors – a factor that
causes population growth to decrease Examples –
• Competition• Predation• Parasitism and disease
Limits on growth Limiting factors – a factor that
causes population growth to decrease Examples –
• Competition• Predation• Parasitism and disease• Drought and other climate extremes
Limits on growth Limiting factors – a factor that
causes population growth to decrease Examples –
• Competition• Predation• Parasitism and disease• Drought and other climate extremes• Human disturbances
Limits on growth Density-dependent factors -
Limits on growth Density-dependent factors – a
limiting factor that depends on population size;
Limits on growth Density-dependent factors – a
limiting factor that depends on population size; limits only when population density reaches a certain level
Limits on growth Density-dependent factors –
Growth rate _________ as density _________
Limits on growth Density-dependent factors –
Growth rate decreases as density increases
Limits on growth Density-dependent factors –
Growth rate decreases as density increases
Growth pattern -
Limits on growth Density-dependent factors –
Growth rate decreases as density increases
Growth pattern – “S” shaped curve
Density-dependent factors Competition
Density-dependent factors Competition
When populations become crowded, organisms compete, or struggle, with one another for food, water, space, sunlight, and other essentials of life
Density-dependent factors Competition
When populations become crowded, organisms compete, or struggle, with one another for food, water, space, sunlight, and other essentials of life
The more individuals that live in an area, the sooner they will use up the available resources
Density-dependent factors Predation -
Density-dependent factors Predation – predator-prey relationship
As the wolves prey on the moose, the moose population _________
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Predation – predator-prey relationship
As the wolves prey on the moose, the moose population decreases
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Predation – predator-prey relationship
This decline is soon followed by _________in the wolf population
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Predation – predator-prey relationship
This decline is soon followed by decreasein the wolf population
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Predation – predator-prey relationship
This decline (of wolf) means the moose has fewer enemies and will therefore eventually ________
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Predation – predator-prey relationship
This decline (of wolf) means the moose has fewer enemies and will therefore eventually increase
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Predation – predator-prey relationship
This cycle continues indefinitely
moose wolf
0
60
30
0
1200
2400Wolf and Moose population on Isle Royale
Density-dependent factors Parasitism and disease -
Density-dependent factors Parasitism and disease –
Example-
Density-dependent factors Parasitism and disease –
Example- eggs of parasitic wasp inserted beneath skin of larval moth (caterpillar)
Limits on growth Density-independent factors -
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size Examples -
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size Examples –
• Unusual weather
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size Examples –
• Unusual weather• Natural disasters
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size Examples –
• Unusual weather• Natural disasters• Seasonal cycles
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size Examples –
• Unusual weather• Natural disasters• Seasonal cycles• Certain human activities
Limits on growth Density-independent factors – affect
all populations in similar ways, regardless of the population size Examples –
• Unusual weather• Natural disasters• Seasonal cycles• Certain human activities
• Damming rivers and clear-cutting forest
Density-independent factors Specific examples -
Density-independent factors Specific examples –
Storms or hurricanes
Density-independent factors Specific examples –
Storms or hurricanes • Insects that feed on plant buds and leaves
might be washed out by heavy rainstorms
Density-independent factors Specific examples –
Extreme cold or hot weather
Density-independent factors Specific examples –
Extreme cold or hot weather• Severe winter frost can kill many plants
Density-independent factors Specific examples –
Periodic droughts
Density-independent factors Specific examples –
Periodic droughts • Can affect entire populations of grasses
• Consumers in food web will then be affected
Human population growth
Human population growth In the United States and developed
countries, the current growth rate is ________
Human population growth In the United States and developed
countries, the current growth rate is very low
Human population growth In the United States and developed
countries, the current growth rate is very low
In some developing countries, the human population growth is nearly _______
Human population growth In the United States and developed
countries, the current growth rate is very low
In some developing countries, the human population growth is nearly 3 people per second
Human population growth
• In some developing countries, the human population growth is nearly 3 people per second
• Because of this, the human population is well on its way to reaching ____________ in your lifetime
Human population growth
• In some developing countries, the human population growth is nearly 3 people per second
• Because of this, the human population is well on its way to reaching 9 billion in your lifetime
Human population growth For most of human existence, the
population grew ______
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth For most of human existence, the
population grew slowly
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth About 500 years ago, the population
began growing more rapidly because life was made easier by _______ and ______
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth About 500 years ago, the population
began growing more rapidly because life was made easier by agriculture and industry
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth With these advances, the human
population experienced ____________
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth With these advances, the human
population experienced exponential growth
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth Human population cannot keep growing
exponentially forever because
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins
Human population growth Human population cannot keep growing
exponentially forever because Earth and its resources are limited.
Human population growth
Agriculturebegins
Plowing And irrigation
Bubonicplague
IndustrialRevolution begins