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Questions and Answers
What is an example of a density-independent factor that influences population growth?
How does increasing food supply affect a population's carrying capacity?
What does population size calculation involve?
Which of the following factors does NOT typically depend on population size?
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Which statement is true regarding a population's carrying capacity?
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The intrinsic growth of a population primarily occurs under which conditions?
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Which of these factors restricts population growth based on density?
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What does a population distribution that is often clumped indicate?
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What does carrying capacity (k) refer to?
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What event marks the beginning of a die-off in a population?
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How does a high population density affect a species?
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What is one factor that does NOT influence population distribution?
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What is implied by a population's age structure?
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In predator-prey dynamics, what follows an increase in hare population?
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What does population sex ratio indicate?
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What typically occurs when a population overshoots its carrying capacity?
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What type of population distribution is characterized by individuals being spaced out evenly across an area?
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What defines a metapopulation?
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How does logistic growth differ from exponential growth?
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What can lead to a skewed sex ratio in a population?
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What describes the 'J-shaped curve' in population models?
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What can cause a population to experience a die-off?
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What is the intrinsic growth rate of a population?
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Which of the following best describes density-independent factors?
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Study Notes
Carrying Capacity
- Carrying Capacity (k): the maximum number of individuals in a population that an ecosystem can support based on limiting resources
- Fig. 1 (theoretical) shows a steady population that reaches its carrying capacity and stabilises there
- Fig. 2 (realistic) shows a population that overshoots its carrying capacity, resulting in a die-off
- The Reindeer of St. Paul Island example illustrates how a population can overshoot its carrying capacity and crash due to resource depletion (lichen in this case)
- Predator-Prey populations fluctuate, with the predator population increasing when the prey population is high, and vice versa
- Real populations do not always fluctuate around carrying capacity; if resource depletion is severe enough, a complete population crash can occur
Population Growth & Resource Availability
- Population size, density, distribution, sex ratio, age structure, and abundance are all factors that affect population growth
- Population size (N) refers to the total number of individuals in a given area at a given time
- Population density refers to the number of individuals per unit area at a given time
- Population distribution is a spatial pattern that describes how individuals in a population are spaced out
- Individuals can be distributed randomly, uniformly, or clumped
- Metapopulations are groups of spatially separate populations that are connected by occasional movements of individuals between them
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Exponential Growth Model
- Intrinsic growth rate is the potential for growth under ideal conditions with unlimited resources, as represented by a J-shaped curve on a graph
- The exponential growth model is defined by the rate at which offspring are produced minus the deaths of individuals or offspring during the same period
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Logistic Growth Model
- Logistic growth is a more realistic model of population growth, where population growth is initially exponential but slows down as the population approaches carrying capacity
- The logistic growth model is represented by an “S” shaped curve on a graph
- If food becomes scarce, the population can experience an overshoot where the population becomes larger than the carrying capacity, leading to a population crash
- Biotic Potential: the maximum potential growth rate in the absence of limiting resources
- Logistic Growth: initial rapid growth as described by biotic potential followed by a leveling off as limiting factors restrict population growth to its carrying capacity
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Factors affecting Population Growth
- Density-Independent Factors: These factors affect population growth regardless of population size and include natural disasters like floods, hurricanes, tornados, and fires
- Density-Dependent Factors: These factors affect population growth based on the size of the population and include food, competition for habitat, water, light, and even disease
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Specific Examples
- Food is a density-dependent factor, impacting carrying capacity
- Sex ratio is a density-dependent factor, impacting natural breeding rates and recovery from die-off events
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Calculating Population Change
- Population size is calculated using the formula: (Immigrations + births) - (immigrations + deaths)
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Description
This quiz focuses on the concepts of carrying capacity and population growth within ecosystems. It explores factors affecting population dynamics, including resource availability and predator-prey interactions. Understand how populations can stabilize or crash based on environmental constraints and resource depletion.
