Question:
The graphs shown represent the relationship between population size (\(N\)) and population growth rate \(\frac{dN}{dt}\). Which one of the following growth curves represents a density-dependent population that experiences a strong Allee effect?
\includegraphics[width=0.5\linewidth]{44.png}
The graphs shown represent the relationship between population size (\(N\)) and population growth rate \(\frac{dN}{dt}\). Which one of the following growth curves represents a density-dependent population that experiences a strong Allee effect?
\includegraphics[width=0.5\linewidth]{44.png}
\includegraphics[width=0.5\linewidth]{44.png}
Show Hint
To identify an Allee effect:
1. Look for negative growth at very small population sizes.
2. A strong Allee effect includes a critical threshold population size below which the population declines.
3. Growth peaks at intermediate population sizes before declining near carrying capacity.
2. A strong Allee effect includes a critical threshold population size below which the population declines.
3. Growth peaks at intermediate population sizes before declining near carrying capacity.
Updated On: Jan 24, 2025
- P
- Q
- R
- S
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The Correct Option is A
Solution and Explanation
Step 1: Understand the Allee effect.
The Allee effect describes a phenomenon where a population’s growth rate decreases when the population size is very small. This occurs due to challenges such as difficulty finding mates or cooperative behaviors not being effective at low densities. A strong Allee effect results in a critical population size below which the population declines to extinction.
Step 2: Identify the characteristics of the growth curve.
A population with a strong Allee effect will exhibit:
1. Negative growth (\(\frac{dN}{dt}<0\)) for very small \(N\), as the population cannot sustain itself.
2. Positive growth (\(\frac{dN}{dt} > 0\)) as \(N\) increases beyond a critical threshold.
3. A peak in growth rate at an intermediate population size.
4. Declining growth (\(\frac{dN}{dt} \to 0\)) as the population approaches carrying capacity.
Step 3: Analyze the graphs.
Graph P: Correct. This graph represents the strong Allee effect, showing negative growth for small \(N\), a critical threshold, and a peak at intermediate \(N\).
Graph Q: Incorrect. This graph shows logistic growth, which does not include negative growth at small \(N\).
Graph R: Incorrect. This graph shows continuous positive growth rates at all population sizes, inconsistent with the Allee effect.
Graph S: Incorrect. This linear growth pattern does not capture the density-dependent dynamics of the Allee effect.
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