Populations Notes

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Do fruit flies and rabbits show similar trends in
population growth?

• Using Tables and Graphs Make a graph using the
  data in each data table. One graph will show the
  growth rate of a fruit fly population. The other
  graph will show the growth rate of a population
  of rabbits.
• Analyzing Data What type of growth pattern is
  exhibited by the fruit fly population? Is it the
  same type of growth as in the rabbit population?
  Explain.
• Drawing Conclusions Does either graph indicate
  that there is a carrying capacity for the
  population? If so, when does the population reach
  its carrying capacity? What is the maximum number
  of individuals that can be supported at that
  time?
• Predicting Animals such as foxes and cats often
  prey on rabbits. Based on the growth curve of the
  rabbit population, what might have happened if a
  group of predators moved into the rabbits
  habitat during the tenth generation and began
  eating the rabbits?
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Populations Notes
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4 Important Characteristics of Populations

• Geographic Distribution
• Population Density
• Growth Rate
• Age Structure

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4 Important Characteristics of Populations

• Geographic Distribution

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4 Important Characteristics of Populations

• Geographic Distribution- or range, the area
  inhabited by a population

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4 Important Characteristics of Populations

• Population Density

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4 Important Characteristics of Populations

• Population Density- Number of individuals in a
  population per unit area

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4 Important Characteristics of Populations

• Growth Rate

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4 Important Characteristics of Populations

• Growth Rate- How fast a population is growing

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4 Important Characteristics of Populations

• Age Structure

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4 Important Characteristics of Populations

• Age Structure- The relative ages of individuals
  in a population

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Factors affecting population growth

• Immigration (im-uh-gray-shun), the movement of
  individuals into an area, is another factor that
  can cause a population to grow.
• Emigration (em-uh-gray-shun), the movement of
  individuals out of a population, can cause a
  population to decrease in size.
• Birth Rate
• Death Rate

People emigrated from here
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2 Types of Population Growth

• Exponential Growth
• Logistic Growth

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2 Types of Population Growth

• Exponential Growth (also called a J shaped
  curve) Growth that occurs when individuals
  reproduce at a constant rate.
• Under ideal conditions with unlimited resources,
  a population will grow exponentially

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2 Types of Population Growth

• Logistic Growth- S shaped curve This shows
  growth slowing or stopping after a period of
  exponential growth.
• Carrying Capacity- the largest number of
  individuals a given environment can support
• How could growth
• slow or stop?

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• How population growth may slow
• Birth rate decreases
• Death Rate Increases
• Both occur at the same rate
• Reason why these change ? Limiting factors

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Limits to Growth

• Limiting Factors- A factor that causes population
  growth to decrease

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Limits to Growth

• Types of limiting factors
• Density-Dependant Factors- a limiting factor that
  depends on a population size.
• Competition, predation, parasitism, and disease
  are examples.

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Density-Dependant Factors

• Competition ? When populations become crowded,
  organisms compete, or struggle, with one another
  for food, water, space, sunlight, and other
  essentials of life.

I only have 5 bottles left
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Density-Dependant Factors

• Predation- The greater the density of predators
  or prey effect the population of the other

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Density-Dependant Factors

• Parasitism and Disease  - Parasitism and disease
  spreads quicker and effects more with greater
  population density.

Wasp Cocoons This larval sphinx moth has been
attacked by a parasitic wasp. The wasp inserted
its eggs beneath the moths skin. After hatching,
the wasp larvae fed on their host internally
until they appeared as white cocoons on its back.
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Density Independent Factors

• affect all populations in similar ways,
  regardless of the population size

Unusual weather, natural disasters, seasonal
cycles, and certain human activitiessuch as
damming rivers and clear-cutting forestsare all
examples of density-independent limiting factors
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Human Population Growth
Human Population has been increasing with time
but cant continue exponentially because we have
limited resources
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Patters of Population Growth

• Demography- the scientific study of human
  populations
• The Demographic transition- A change in a
  population from high birth and death rates to low
  birth and death rates.

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Age Structure

• Age structure diagram- a population profile,
  graphs the numbers of people in different age
  groups in the population