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Difficulty: Very hardStructural Adaptations for Survival: Coloration, Camouflage, and Mimicry

In a forest ecosystem, a population of non-venomous scarlet kingsnakes (*Lampropeltis elapsoides*) displays red, black, and yellow ring patterns that closely resemble those of the venomous eastern coral snake (*Micrurus fulvius*). Field studies indicate that the survival advantage of the kingsnake's color pattern decreases significantly when the population density of the coral snake drops below a critical threshold. Which of the following best explains why this structural adaptation loses its defensive efficacy under low model density?

  1. Predators fail to associate the bright warning coloration with a negative stimulus when encounters with the harmless mimic outnumber those with the unpalatable model.Answer
  2. B
    The pattern represents cryptic coloration, which fails to blend into the surrounding vegetation unless model species are present in large numbers.
  3. C
    The relationship is an instance of Müllerian mimicry, which requires both species to maintain strictly equal population sizes for shared warning signals to function.
  4. D
    Environmentally acquired color modifications in the kingsnake rapidly degrade across generations when predator hunting pressure is reduced.

Answer

Predators fail to associate the bright warning coloration with a negative stimulus when encounters with the harmless mimic outnumber those with the unpalatable model.
Batesian mimicry operates via frequency-dependent selection. Predators learn to avoid conspicuous aposematic coloration after unpleasant encounters with the toxic model. If the toxic model's population density is low relative to the harmless mimic, predators are more likely to sample the mimic without experiencing harm, preventing or breaking the learned avoidance behavior.

Step-by-Step Solution

1
Identify the type of structural adaptation described in the scenario.
The harmless kingsnake copying the warning signal of the dangerous coral snake is an example of Batesian mimicry.
Batesian mimicry involves a palatable/harmless mimic gaining protection by resembling a unpalatable/dangerous model.
2
Analyze the ecological mechanism governing predator learning in Batesian mimicry.
Predator avoidance of the warning signal depends on frequency-dependent reinforcement.
Predators must encounter the toxic model frequently enough to form a strong association between the bright warning signal (aposematism) and noxious consequences.
3
Evaluate the effect of low model density on mimic survival.
When the model density drops, predators encounter the harmless mimic more often, unlearning or failing to acquire the avoidance behavior.
Without sufficient negative reinforcement from the model, predators treat the mimic as rewarding prey, causing the mimic's protective advantage to collapse.

Key Concept

Batesian Mimicry and Frequency-Dependent Selection
Estimated Time:1m 30s
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Topics

Structural Adaptations for Survival: Coloration, Camouflage, and Mimicry

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