Population Growth and Regulation
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Questions and Answers

What is the key concept of exponential growth?

  • Population size remains constant over time
  • The growth rate remains constant over time
  • The population size increases at a constant rate
  • The growth rate increases over time (correct)

    • What term is used to describe the maximum population size that a particular environment can sustain?

  • Growth capacity
  • Carrying capacity (correct)
  • Expansion threshold
  • Reproductive limit

    • In logistic growth, what happens to the growth rate as resources become scarce?

  • It decreases (correct)
  • It remains constant
  • It fluctuates
  • It increases

    • What type of growth curve is produced when resources are limited?

    <p>S-shaped curve</p> Signup and view all the answers

    What occurs when a population overshoots its carrying capacity?

    <p>The death rate increases</p> Signup and view all the answers

    Why is the J-shaped growth curve not representative of real-world populations?

    <p>Because it indicates unlimited resources</p> Signup and view all the answers

    What did Charles Darwin describe in his concept of the 'struggle for existence'?

    <p>'Survival of the fittest'</p> Signup and view all the answers

    In logistic growth, what happens to the population once it reaches the carrying capacity?

    <p>It levels off and maintains stability</p> Signup and view all the answers

    'Survival of the fittest' refers to individuals who:

    <p>Are most successful in reproducing and passing on traits</p> Signup and view all the answers

    Which model of population growth describes populations that increase in numbers without any limits?

    <p>Exponential growth</p> Signup and view all the answers

    Which scientist influenced Charles Darwin with his ideas about population growth?

    <p>Thomas Malthus</p> Signup and view all the answers

    Which organisms provide the best example of exponential growth?

    <p>Bacteria</p> Signup and view all the answers

    What is the characteristic of the logistic growth model?

    <p>It introduces limits to reproductive growth that become more intense as population size increases.</p> Signup and view all the answers

    Which statement is true about the two population growth models discussed?

    <p>Neither model adequately describes natural populations.</p> Signup and view all the answers

    What is the purpose of population growth models, according to the text?

    <p>To describe and predict changes occurring in a population over time</p> Signup and view all the answers

    What is the shape of the growth curve exhibited by yeast in a test tube?

    <p>S-shaped</p> Signup and view all the answers

    What is the main reason the logistic growth model is a simplification of real-world population dynamics?

    <p>All of the above</p> Signup and view all the answers

    What is the main difference between the growth curves of yeast in a test tube and the harbor seal population in the wild?

    <p>The seal curve has more scatter in the data points</p> Signup and view all the answers

    What is the main reason for the extinction of the woolly mammoth?

    <p>Both climate change and human hunting</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the logistic growth model?

    <p>The population size can exceed the carrying capacity for short periods</p> Signup and view all the answers

    What is the main purpose of the images in Figure 2?

    <p>To demonstrate the differences between the yeast and seal growth curves</p> Signup and view all the answers

    How did the range of the woolly mammoth change over time?

    <p>It decreased from 3,000,000 square miles to 310,000 square miles</p> Signup and view all the answers

    Why did the woolly mammoth population on Wrangel Island survive longer than other populations?

    <p>The mammoths on the island were isolated from human contact</p> Signup and view all the answers

    Which of the following is NOT a factor that can affect the carrying capacity of an environment?

    <p>The size of the geographic area occupied by the population</p> Signup and view all the answers

    What is the main purpose of the images in Figure 3?

    <p>To show the physical appearance of woolly mammoths</p> Signup and view all the answers

    The logistic growth model accurately represents the population dynamics of all real-world populations.

    <p>False</p> Signup and view all the answers

    The extinction of the woolly mammoth was primarily due to climate change.

    <p>True</p> Signup and view all the answers

    The population of harbor seals shown in Figure 2b exhibits a perfectly smooth logistic growth curve.

    <p>False</p> Signup and view all the answers

    The carrying capacity of an environment is constant and does not change over time.

    <p>False</p> Signup and view all the answers

    The woolly mammoth population on Wrangel Island went extinct at the same time as other mammoth populations.

    <p>False</p> Signup and view all the answers

    Study Notes

    Population Growth

    • Population growth can be modeled using two simple models: exponential growth and logistic growth
    • Exponential growth: population size increases rapidly without limits, leading to a J-shaped growth curve
      • Example: bacteria growth in a flask with abundant resources
      • Key characteristic: growth rate increases with each reproductive generation
    • Logistic growth: population growth slows down as resources become limited, leading to an S-shaped growth curve
      • Example: yeast growth in a test tube, sheep and harbor seal populations
      • Key characteristic: growth rate slows down as resources become limited, and population size levels off at the carrying capacity

    Carrying Capacity

    • The carrying capacity is the maximum population size that a particular environment can sustain
    • In logistic growth, the population size fluctuates around the carrying capacity
    • Factors that can affect carrying capacity:
      • Environmental changes (e.g. hot and dry summers, cold and wet winters)
      • Natural events (e.g. earthquakes, volcanoes, fires)
      • Interspecific competition (competing with other species for resources)

    Examples of Logistic Growth

    • Yeast growth in a test tube: classical S-shaped curve, growth levels off as nutrients are depleted
    • Sheep and harbor seal populations: population size exceeds carrying capacity for short periods, then falls below it
    • These examples show that the logistic model is a simplification of real-world population dynamics

    Population Dynamics and Regulation

    • The logistic model is a simplification of real-world population dynamics
    • Factors that affect population growth:
      • Carrying capacity varies annually
      • Natural events can alter the environment and its carrying capacity
      • Interspecific competition affects population growth

    Why Did the Woolly Mammoth Go Extinct?

    • Most populations of woolly mammoths went extinct about 10,000 years ago

    • Reasons for extinction:

      • Climate change reduced the mammoth's range
      • Human hunting contributed to their extinction

    • A mammoth population survived on Wrangel Island until 1700 BC### Population Growth Models

    • Exponential growth: occurs when resources are unlimited, and the population grows at an increasing rate, resulting in a J-shaped curve.

    • Logistic growth: occurs when resources are limited, and the population growth slows down and eventually levels off, resulting in an S-shaped curve.

    Exponential Growth

    • In a controlled environment with abundant resources, bacteria can double in number every hour, leading to rapid exponential growth.
    • This type of growth is only possible with unlimited resources, which is not the case in the real world.

    Logistic Growth

    • This model takes into account the limited resources in the environment and the competition for those resources.
    • The population grows rapidly at first, but as resources become scarce, the growth rate slows down and eventually levels off at the carrying capacity.
    • The carrying capacity is the maximum population size that the environment can sustain.

    Carrying Capacity

    • It is the maximum population size that a particular environment can sustain.
    • It varies annually and can be affected by natural events such as earthquakes, volcanoes, and fires.
    • It is also affected by interspecific competition, where different species compete for the same resources.

    Examples of Logistic Growth

    • Yeast in a test tube: exhibits a classical S-shaped logistic growth curve as the population depletes the nutrients necessary for its growth.
    • Harbor seals: in the wild, the population size exceeds the carrying capacity for short periods, and then falls below it, resulting in oscillation around the carrying capacity.

    Population Dynamics and Regulation

    • The logistic model is a simplification of real-world population dynamics.
    • The carrying capacity of the environment does not remain constant and can vary due to natural events and interspecific competition.

    Extinction of the Woolly Mammoth

    • Most populations of woolly mammoths went extinct around 10,000 years ago.
    • Climate change and human hunting are thought to be the main reasons for their extinction.
    • A 2008 study estimated that climate change reduced the mammoth's range from 3,000,000 square miles to 310,000 square miles over time.

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    Description

    Learn about population dynamics, models of population growth, and methods used by population ecologists to predict future changes in a population. This quiz explores deterministic equations, exponential growth, and logistic growth in the context of population ecology.

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