托福口语 Task 4

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Question: Using the examples from the lecture, explain the professor's main point about Batesian mimicry and its effectiveness.

🎧 听力讲座

Today we're going to discuss a fascinating aspect of animal behavior known as 'biological mimicry' — where one species evolves to resemble another for survival. Specifically, I want to focus on a type called 'Batesian mimicry', where a harmless species mimics a dangerous or unpalatable one to avoid predators. The key point is that this mimicry only works if the mimic is less common than the model, because predators must first learn to avoid the dangerous model. Let me give you two examples. First, consider the scarlet king snake, which is harmless, but its red, yellow, and black bands closely resemble the venomous coral snake. Predators that have had a bad experience with coral snakes will avoid the king snake too. However, in areas where coral snakes are rare and king snakes are abundant, predators may not learn the association, and the mimicry fails. Second, think of certain harmless hoverflies that mimic the yellow and black stripes of stinging wasps. Birds that have tried to eat a wasp quickly learn to avoid anything with those stripes. So, the hoverfly benefits, but only if wasps are plentiful enough in the environment to teach predators the lesson.

📝 参考答案

托福口语 Task 4 评分标准

总分30分,原始分0-4分,最终换算为30分制。

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