Listen to part of a lecture in a biology class. Professor: Today we're going to talk about mimicry in animals, specifically Batesian mimicry. This is a phenomenon where a harmless species evolves to resemble a harmful or toxic species, thereby gaining protection from predators. For example, the scarlet king snake, which is non-venomous, mimics the color pattern of the deadly coral snake. Predators that have learned to avoid the coral snake will also avoid the king snake. But here's an interesting twist: for mimicry to be effective, the harmful model must be more common than the mimic in the same area. If the mimic becomes too abundant, predators will encounter it more often and may realize it's not dangerous, leading to the breakdown of the mimicry. This is known as frequency-dependent selection. So the relative population sizes are crucial. Now, what happens if the model disappears from the area? The mimic would then lose its protection and become vulnerable to predation, which could lead to its decline.
❓ Question What is the key condition for Batesian mimicry to remain effective, according to the professor?
A. The mimic must be more numerous than the model.
B. The model must be more common than the mimic in the same area.
C. The mimic must be venomous itself.
D. The predator must be able to distinguish between the model and the mimic.
✅ Correct Answer
The model must be more common than the mimic in the same area.
TOEFL Listening Tips
Skim the questions first to predict the content
Watch for signal words in lectures and conversations (however, actually, in fact)
For main idea questions, focus on the beginning; for detail questions, focus on examples and data
For attitude questions, pay attention to the speaker's tone and word choice
Take notes on keywords; don't try to write down every word
