POPULATIONS

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POPULATIONS
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1. S curve Logistic growth
When we look at how populations grow, we can
observe 2 types of growth curves 1. S shaped
curve- Logistic growth 2. J shaped
curve- Exponential growth

• Resource availability will cause the population
  to level off over time

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2. J curve Exponential growth J Shape

• Happens during ideal conditions
• Plenty of food, shelter etc.
• Unlimited resources
• No limiting factors
• POPULATION EXPLOSION

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• Horizontal line where growth of the population
  has leveled off is the CARRYING CAPACITY
• Carrying Capacity The number of individuals in
  a population that an environment can support over
  a long period of time
• As growth continues, the environment's resources
  are shared by more and more individuals.
• Eventually, some resources are in short supply
  and become a limiting factor
• Determine an environments carry capacity
• things that prevent a population from growing any
  larger

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In the graph below, what factors would cause the
growth rate to decrease or level off?
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Limiting Factor a factor that causes the growth
of a population to decrease.

• 1. Density dependent (biotic)
• Competition may use same food, or shelter.
• Predation predatorprey curve (pop. control)
• Parasitism and disease
• 2. Density independent (abiotic)
• Natural disasters
• Human disturbances (construction)
• Weather

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How does the difference in water temperature
affect the growth rate of the three species of
fish depicted in the graph?
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GROUP ACTVITY.QUESTION Has the Earth reached
its carrying capacity for Humans?

• Based on what you have learned about carrying
  capacity, answer the
• following questions.
• Some scientists believe we have passes Earths
  Carrying capacity for humans. Some believe we may
  reach it when the human population reaches 12
  billion.
• In your opinion, has the earth passed its
  carrying capacity? Justify your answer.
• - Give 3 reasons to support each argument.
• What would limit humans from increasing its
  population indefinitely?

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EXPONENTIAL LOGISTIC GROWTH CURVES WKST
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PREDATOR PREY CURVE