Аудирование TOEFL

🎧 Транскрипт аудио

Narrator: Listen to part of a lecture in a biology class. Professor: Today we're going to talk about mimicry, specifically how certain harmless species have evolved to imitate dangerous ones. This is called Batesian mimicry. For example, the scarlet king snake, which is harmless, has red, yellow, and black bands very similar to the venomous coral snake. Predators that have learned to avoid the coral snake also avoid the king snake. But here's an interesting twist: for mimicry to work, the mimic must be less common than the model. If the mimic becomes too abundant, predators might start to realize that not all snakes with those colors are dangerous, and the protection breaks down. Also, the mimic doesn't have to copy every detail perfectly; just enough to fool the predator at a glance. This raises a question: why don't mimics become perfect copies? One reason is that predators use multiple cues, like size or behavior. And also, the mimic may face trade-offs, like needing to blend into its own environment for hunting. So natural selection favors a balance, not perfection.