- Incorporating additional ecological factors into the Lotka-Voltera predator-prey model can change the predator isocline. Given below are three state-space graphsA-C) representing modification of predator isocline due to the ecological factors listed below (i-iii).
(i) Victim abundance acting as predator carrying capacity
(ii) Availability of alternate prey (victim) population
(iii) Predator carrying capacity determined by factors other than victim abundance.
Which one of the following options represents all correct matches of the state space
graphs with their ecological factor?
(1) A — (ii), B — (iii), C — (i)
(2) A — (ii), B — (i), C – (iii)
(3) A — (iii), B — (ii), C — (i)
(4) A — (i), B — (ii), C — (iii)The Lotka-Volterra predator-prey model is a foundational tool in ecology, describing how predator and prey populations interact over time. In its basic form, the model assumes simple dynamics, but real ecosystems are influenced by additional ecological factors. These factors can significantly alter the shape and position of the predator isocline (the line where predator population growth is zero) in state-space graphs.
Key Ecological Factors That Modify the Predator Isocline
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Victim abundance acting as predator carrying capacity: Here, the predator’s maximum population is directly limited by the abundance of its primary prey. The isocline will curve or level off as prey numbers increase, showing a direct dependence on prey for predator sustainability.
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Availability of alternate prey (victim) population: If predators can switch to alternate prey, their population can be maintained even when the focal prey is scarce. This introduces a vertical or shifted isocline, as predator persistence is less tightly linked to the original prey’s abundance.
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Predator carrying capacity determined by factors other than victim abundance: When predator numbers are limited by resources or factors other than the focal prey (such as territory or nesting sites), the predator isocline becomes a horizontal line, showing independence from prey density at higher values.
Matching State-Space Graphs with Ecological Factors
Given the three state-space graphs (A, B, C) and ecological factors (i–iii), the correct matches are:
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A — (ii): Availability of alternate prey (victim) population
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The isocline is vertical or offset, indicating that predators can survive even if the main prey is rare, thanks to alternate food sources.
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B — (i): Victim abundance acting as predator carrying capacity
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The isocline levels off or curves, showing that predator numbers are capped by how many prey are available.
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C — (iii): Predator carrying capacity determined by factors other than victim abundance
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The isocline is horizontal, indicating predator numbers are set by non-prey factors and do not increase with more prey beyond a certain point.
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Correct Option
The correct answer is:
(2) A — (ii), B — (i), C — (iii)
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