GROWTH MODELS

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GROWTH MODELS

• pp. 383-387

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• birth rate of births occurring in a given
  amount of time
• death rate of deaths occurring in a given
  amount of time
• Population growth of births is greater than
  the of deaths
• Zero population growth
• of births is equal to of deaths

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REGULATING POPULATION SIZE AND GROWTH

• Limiting factors restrains population growth
• Density-independent factors no regard for
  population density
• EX. Weather, seasons, natural disasters
• Density-dependent factors increase or become
  more prominent when the population density
  increases
• EX. predation, pollution, food shortage

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EXPONENTIAL MODEL
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• EXPONENTIAL MODEL
• Increase on the y axis (population size) much
  faster than on the x axis (time)
• The larger the population, the faster it grows
• birth and death rates are constant (b gt d)
• limited by density-independent factors

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LOGISTIC MODEL
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• Starts off exponential (bgt d)
• Levels off as it reaches carrying capacity (K
  maximum number of individuals an environment can
  sustain)
• This is when b d rates (zero population growth)
  
• Limited by density-dependent factors