Population Dynamics and Growth

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Population Dynamics and Growth

• Pre AP Biology
• Spring 12

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Competition

• Competition occurs when 2 or more species use the
  same resource.
• Examples of the resource are
• Food
• Light
• Space
• Shelter
• Water
• Nesting sites

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Limiting factors

• Limiting factors are the biotic and abiotic
  factors in an ecosystem that limits the
  existence, numbers or reproduction the organisms
  in that environment.

Popu l a t i on
Zone of stress optimum conditions
stress zone of Intolerance in
tolerance
Low ENVIRONMENTAL FACTOR High
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Limiting Factors

• Examples of limiting factors
• Temperature organisms have an optimum
  temperature range in which they can survive.
• CO2 levels
• O2 levels
• Humidity
• Amount of sunlight
• Prey availability
• Mineral availability

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Kinds of Limiting Factors

• Density-dependent has an increasing effect as
  population increases. Usually biotic.
• ex disease, parasites, competition for food
• Density-independent has an effect on all
  populations regardless of their population.
  Usually abiotic.
• ex sunlight, temperature

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How Predation Helps

• Predators help keep population size within the
  limits of available resources.

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Limiting factor graph (example)

• Graph the temperature tolerance for 2 species of
  plants (aloe vera and ivy). The data is in sets
  of three
• A, B, C A temperature
• B number of aloe vera
• C number of ivy
• Use 2 different colors. Remember every graph
  needs a title, x and y axis labeled, and a legend

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Data

• 0,0,0
• 10,0,0
• 20,0,2
• 30,0,10
• 40,2,20
• 50,5,40
• 60,10,60
• 70,12,70
• 80,30,60
• 90,50,30
• 100,40,10
• 110,20,2
• 120,5,0
• 130,0,0
• 140, 0,0

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Practice

• Make a tolerance graph for 2 kinds of small
  mammals. Highlight the zones of intolerance for
  both and place a star at the optimum temperature
  for both. The first number is temperature, the
  second is the population of arctic hare and third
  number is the population of jackrabbit.
• 0,20,0
• 20,40,0
• 40,20,10
• 60,0,15
• 80,0,30
• 100,0,25
• 120,0,0

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Practice

• Make a tolerance graph for 2 kinds of fish.
  Highlight the zones of intolerance for both and
  place a star at the optimum salinity ( of salt
  in water) for both. The first number is the
  salinity (parts per million) , the second is the
  population of trout and third number is the
  population of sea bass.
• 0, 0, 0
• 2, 10, 0
• 4, 20, 0
• 8, 60, 0
• 10, 40, 2
• 15, 10, 10
• 20, 2, 50
• 25, 0, 35
• 30, 0, 15
• 40, 0, 0

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Population Growth

• Population growth is a change in population with
  time
• 3 kinds of growth graphs
• Linear growth
• Exponential growth
• Logistic growth

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Logistic is most common

• Linear growth almost never occurs. It assumes
  the exact same rate of growth. (If every 2
  people had 3 childrenwed replace ourselves 1)
• Population growth is sometimes exponential if
  resources are unlimited
• Logistic growth is the most common because it
  represents exponential growth until resources
  limit growth and it levels out.

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Carrying capacity

• Carrying capacity number of organisms of a
  population that an environment can support
• 2 kinds of strategists or patterns of population
  growth
• r-strategists
• k-strategists

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R-strategists

• Have a rapid period of population growth
• The rapid growth far exceeds carrying capacity
• Rapid growth followed by a crash
• After the crash there is another period of rapid
  growth, etc.
• This organisms have many offspring, dont care
  for their young, and have short life
• Examples bugs and fish

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K-strategists

• Have a long period of slow growth
• Then they reach the carrying capacity.
• At that point they have minor fluxuations in
  growth around carrying capacity.
• They have few young, a long life, and tend to
  take care of their young.
• Examples most mammals

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Homework

• Answer the following questions about the graph.
• Give the zones of intolerance for aloe vera and
  for ivy?
• What is the optimum temperature for aloe vera?
• Which plant grows better outside in South Texas?
• How could a person who owns a gardening store use
  this information?

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Pre AP homework

• 5. Read page 370 and answer question 2 and 3
  on page 370. I expect more than a sentence
  answer. Your answers should fill more than a half
  a page.