2016 Unit 4 Growth Curves.notebook
June 09, 2016
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
Population Growth Curves
2 general types
This is a J shaped curve.
It shows the population
starting off low, growing
slowly at first, and then
growing quickly. No
limits to population size.
This may also be called an exponential growth curve.
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
As indicated, this one is
called the S curve. It
shows a population starting
off with a few members
and showing slow growth at
the beginning, followed by
a period of rapid growth,
and then a period of
stabilization.
This one is sometimes called the logistic growth curve.
If we add this purple line to the top of the
graph, where the growth curve levels off, we
get the CARRYING CAPACITY of the
environment in which this population is
located. This number is the number of
organisms of this type that the environment
can support. Any more than this, and the
environment would be over-extended, and we
would begin to see environmental resistance
However, the population will try to produce as many
offspring as possible. The maximum number of offspring
a population can produce is its biotic potential.
Carrying capacity is a balance
between the environment trying
to keep the population down, and
the population trying to get the
numbers up. Where these two
opposing forces meet is the
carrying capacity.
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
The Predator/Prey Relationship
Predators: Fox, Lynx, Bear, etc.
Prey: rabbit, hare, salmon, etc.
Note the relationship between the
populations of predator and prey. As the
prey population declines, the predator
population has to decline, because there are
not enough resources there for a large
number of predators. But once the predator
population shrinks, the prey population can
rebound and grow to larger numbers. This
allows the predator numbers to increase
again, and so on.
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
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2016 Unit 4 Growth Curves.notebook
Stage 1:
June 09, 2016
Birth rate is high
Death rate is high
Population size remains low (little or no growth)
Stage 2:
Death rate starts to decline (advances in medicine, sanitation, food production, etc)
Birth rate remains high
Population size starts to increase
Stage 3:
Death rate is starting to level off at a low rate
Birth rate declines because more offspring are surviving (therefore, women have fewer children)
Population growth rate begins to slow down.
Stage 4:
Death rate is low.
Birth rate is low.
Population GROWTH is low.
Population size is high.
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
How have human technologies increased the Earth's carrying capacity?
improved farming techniques
fishing advancements
game reserves
renewable energy resources
environmentally­friendly products
drinking water purification
using organisms like bacteria to clean up oil spills
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2016 Unit 4 Growth Curves.notebook
June 09, 2016
How have humans decreased the earth's
carrying capacity?
pollution
fishery depletion
deforestation
burning fossil fuels
diseases
increased CO2 production
extinction of species
oil spills/pollution
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