Predator-Prey Cycles in Ecology
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Questions and Answers

What typically happens to the predator population after an increase in the prey population?

  • The predator population decreases gradually.
  • The predator population remains constant.
  • The predator population immediately decreases.
  • The predator population increases after a time delay. (correct)

In the predator-prey cycle, what is the primary role of the 'c' variable in the Lotka-Volterra model?

  • It represents the growth rate of the prey population.
  • It reflects the death rate of the prey population.
  • It denotes the rate of change in the predator population.
  • It indicates the ability of predators to capture prey. (correct)

Under what condition will the prey population increase according to the Lotka-Volterra model?

  • When the death rate of the predator population is low.
  • When the capture efficiency of predators exceeds growth rate of prey.
  • When the growth rate of prey exceeds the product of the predator and prey population. (correct)
  • When the predator population is higher than the prey population.

What length of cycles is observed in large animals like hares and lynxes in Arctic tundra regions?

<p>9-year cycles (B)</p> Signup and view all the answers

Which component of the Lotka-Volterra model is primarily associated with the efficiency of transforming food into population growth for predators?

<p>a (assimilation efficiency) (B)</p> Signup and view all the answers

What is the primary factor that leads to a decline in the prey population during the predator-prey cycle?

<p>Increase in predation due to a larger predator population (C)</p> Signup and view all the answers

In the context of predator-prey cycles, what does the term 'capture efficiency' refer to?

<p>The ability of predators to capture prey (C)</p> Signup and view all the answers

Which of the following statements best describes the Lotka-Volterra model equation for the prey population?

<p>It combines rates of prey population growth and predation. (C)</p> Signup and view all the answers

What happens to the predator population following a decline in the prey population?

<p>It begins to decline due to a lack of food. (A)</p> Signup and view all the answers

Which factor primarily contributes to the growth of the predator population in the Lotka-Volterra model?

<p>Increased availability of prey (D)</p> Signup and view all the answers

What is the time interval between population peaks in the predator-prey cycle typically observed in large animals like hares and lynxes in the Arctic tundra?

<p>9 years (A)</p> Signup and view all the answers

In which situation will the prey population experience growth according to the Lotka-Volterra model?

<p>When the growth rate of the prey exceeds predation (A)</p> Signup and view all the answers

What does the variable 'd' in the predator population equation signify?

<p>Death rate of the predator population (A)</p> Signup and view all the answers

How does the population cycle of small animals differ in frequency compared to larger animals in the Arctic tundra?

<p>Small animals have a 4-year cycle, while large animals have a 9-year cycle. (D)</p> Signup and view all the answers

Which of the following accurately describes the term 'a' in the predator population equation?

<p>Assimilation efficiency of predator food (B)</p> Signup and view all the answers

What describes the relationship between the predator and prey populations in the predator-prey cycle?

<p>An increase in prey leads to a subsequent increase in predators after a time delay. (B)</p> Signup and view all the answers

What is the primary factor that determines whether the prey population will grow, according to the Lotka-Volterra model?

<p>The growth rate of the prey population must surpass the predation rate. (A)</p> Signup and view all the answers

Which variable in the Lotka-Volterra model represents the size of the predator population?

<p>P (A)</p> Signup and view all the answers

Which cycle frequency is typically observed in small animal populations in Arctic tundra regions?

<p>4-year cycles (B)</p> Signup and view all the answers

What does the variable 'a' in the predator population equation represent?

<p>Assimilation efficiency (B)</p> Signup and view all the answers

What is a consequence of an increase in predator population in the predator-prey cycle?

<p>A decline in prey population size. (A)</p> Signup and view all the answers

When analyzing the Lotka-Volterra equations, what does the term 'c' represent?

<p>The ability of predators to capture prey. (A)</p> Signup and view all the answers

In the Lotka-Volterra model, what happens to the prey population when 'rR' is less than 'cRP'?

<p>The prey population decreases. (C)</p> Signup and view all the answers

Which statement accurately describes the relationship seen in predator-prey cycles over time?

<p>Predator populations lag behind those of prey populations. (C)</p> Signup and view all the answers

What is the significance of the period of the cycle in predator-prey dynamics?

<p>It measures the time between population peaks. (D)</p> Signup and view all the answers

What characterizes the Holling Type I functional response?

<p>The predator's consumption rate increases with prey density without cap. (A)</p> Signup and view all the answers

Which type of functional response includes a plateau in the number of prey consumed?

<p>Type II response (C)</p> Signup and view all the answers

What primarily triggers a Type III functional response in predators?

<p>Limited availability of safe hiding places for prey. (B)</p> Signup and view all the answers

What does the numerical response of predators depend upon when a Type II or III response is observed?

<p>Growth of the predator population through immigration or reproduction. (A)</p> Signup and view all the answers

Which of the following is NOT an assumption of the Lotka-Volterra predation model?

<p>Prey populations are independent of predator interactions. (A)</p> Signup and view all the answers

Which statement describes the relationship between prey availability and predator consumption in a Type I functional response?

<p>Predator consumption increases proportionally to prey density without any limits. (D)</p> Signup and view all the answers

What effect does switching behaviors have on predator populations?

<p>It allows predators to adapt to fluctuations in prey availability. (C)</p> Signup and view all the answers

What is a significant limitation of the Lotka-Volterra predation model?

<p>It does not account for environmental factors that affect predator-prey dynamics. (A)</p> Signup and view all the answers

In what situation would a predator most likely exhibit a Type III response?

<p>In heterogeneous habitats with limited prey shelter. (A)</p> Signup and view all the answers

Flashcards

Predator-Prey Cycles

Natural fluctuations in predator and prey populations, often showing cyclical patterns. Predators depend on prey for food, so prey population changes influence predator population changes (and vice-versa).

Lotka-Volterra Predation Model

A mathematical model describing predator-prey interactions, showing how changes in prey and predator population sizes influence each other. It's a simplified representation of the dynamics.

Prey Population Equation

dR/dt = rR – cRP. The change in prey population (dR/dt) is based on prey growth minus the prey lost to predators. r is prey growth rate, c is predator capture rate.

Predator Population Equation

dP/dt = acRP - dP. Change in predator population depends on predator growth based on consuming prey and constant rate of predator death.

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Predator-Prey Cycle Period

The time it takes for a predator-prey cycle to repeat itself.

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Predator-Prey Cycle

Recurring fluctuations in predator and prey populations, driven by the feeding relationship.

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Lynx and Hare

A classic example of a predator-prey relationship with observed cycles in populations.

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9-year Arctic Cycle

Large animals (hares, muskrats, grouse) display population cycles over approximately 9 years in Arctic tundra.

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4-year Small Animal Cycle

Small animals (voles, mice, lemmings) show population cycles roughly every 4 years in Arctic.

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Predator Increase

An increase in prey population provides more food for predators, leading to predator population increase.

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Prey Decrease

Growing predator populations increase predation pressure, which reduces prey population.

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Lotka-Volterra Model

Mathematical model describing predator-prey interactions, predicting population fluctuations.

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Prey Population Equation

dR/dt = rR – cRP. Rate of prey change = prey growth – prey consumed by predators.

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Predator Population Equation

dP/dt = acRP – dP. Predator population change depends on prey eating and predator death.

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Population Cycle Period

The time taken for a predator-prey population cycle to complete – often in years.

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Predator-Prey Cycle

Recurring fluctuations in predator and prey populations, driven by the feeding relationship.

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Lotka-Volterra Model

Mathematical model describing predator-prey interactions, predicting population fluctuations.

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Prey Population Equation

dR/dt = rR - cRP. Rate of prey change is prey growth minus removal by predators

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Predator Population Equation

dP/dt = acRP - dP. Rate of predator change depends on prey consumption and death.

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Population Cycle Period

The time it takes for a predator-prey cycle to repeat.

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Predator-Prey Relationship

The interaction in which one population (predator) feeds on another (prey), influencing both.

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Lynx and Hare

Example of classic predator-prey cycle in North America, with population fluctuations.

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9-year Arctic Cycle

Population cycles observed in large Arctic animals (e.g., hares, muskrats), lasting approximately 9 years,

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4-year Small Animal Cycle

Population cycles observed in smaller Arctic animals (e.g., voles, mice), lasting approximately 4 years.

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Predator Increase

Increase in prey population leads to more food for predators, increasing their numbers.

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Type I Functional Response

Predator consumption rate is directly proportional to prey density; eating rate increases linearly with prey numbers.

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Type II Functional Response

Predator consumption rate increases with prey density but then levels off; predator is satiated at higher prey densities.

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Type III Functional Response

Predator consumption is depressed at low prey densities, increases with prey density reaching a plateau.

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Numerical Response

Increase in predator population in response to increasing prey availability, via reproduction or immigration.

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Lotka-Volterra Model

Simple mathematical model explaining predator-prey cycles; makes specific assumptions.

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Functional Response

How a predator's consumption rate changes with prey density.

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Satiation

When a predator cannot eat any more prey, regardless of how much is available.

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Heterogeneous habitat

An environment with varied or diverse types of areas, like hiding spots for prey.

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Search Image

A mental image or pattern used by a predator to identify and locate prey.

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Switching to alternative food

Predator eats different types of prey when one type is scarce.

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Study Notes

Predator-Prey Cycles

  • Classic example: North American lynx (Lynx canadensis) preys almost exclusively on snowshoe hares (Lepus americanus).
  • Lynx and hare populations exhibit highly synchronized cycles.
  • Graph shows lynx and hare population fluctuations over time.

Predator-Prey Cycles in Arctic Tundra Regions

  • Large animals (hare, muskrat, ruffed grouse) have 9-year cycles.
  • Lynx and red fox are predators of these animals.
  • Small animals (voles, mice, lemmings) have 4-year cycles.
  • Hawks and owls are predators of these animals.

Predator-Prey Cycle Dynamics

  • Prey population increase leads to more food for predators, causing predator population to increase (with a time delay).
  • Increased predator population intensifies predation, decreasing prey population size.

Theoretical Model

  • Prey population size follows cyclical peaks and troughs.
  • Predator population size cycles, lagging behind prey numbers.
  • The period of a cycle (time between peaks) is approximately 10 years.
  • Shows graphical relationships between prey and predator populations.

Lotka-Volterra Predation Model

  • Prey equation: dR/dt = rR – cRP.
    • dR/dt: rate of change in prey population
    • r: growth rate of prey
    • R: size of prey population
    • c: capture efficiency of predator
    • P: size of predator population
  • Predator equation: dP/dt = acRP – dP.
    • dP/dt: rate of change in predator population
    • a: assimilation efficiency
    • d: death rate of predator

When Populations Increase

  • For prey, populations increase when rR > cRP (growth rate > removal rate). Rearranging this results in P < r/c.
  • For predator populations, increase occurs with higher prey and assimilation efficiency.

Equilibrium of Populations

  • Populations are at equilibrium when the rate of change (dR/dt and dP/dt) is zero.
    • dR/dt = rR - cRP = 0; P = r/c
    • dP/dt = acRP - dP = 0; R = d/ac

Equilibrium Isocline

  • Line of zero growth for prey and predator populations.
  • Shows the relationship between prey and predator densities at equilibrium.
  • Graphs illustrate the lines for zero growth for prey and predator populations.

Joint Population Trajectory

  • Cyclic relationship shown as a circular trajectory on a graph with prey density on x-axis and predator density on y-axis.
  • Indicate the cyclical increases and decreases in predator and prey populations.

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Related Documents

Predator-Prey Cycles PDF
Ecology Lecture 16 - Predation PDF

Description

Explore the intricate dynamics of predator-prey relationships, particularly focusing on the North American lynx and snowshoe hare cycles. This quiz examines population fluctuations and the cyclical nature of herbivores and their predators in the Arctic tundra. Delve into the theoretical models that explain these ecological interactions.

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