托福口语 Task 4

Today, we're going to talk about a fascinating concept in animal behavior called 'mimicry for defense'. Now, mimicry is when one species evolves to look like another species in order to gain some advantage. But not all mimicry is about looking dangerous. Sometimes, it's about looking unappealing or even confusing. Let me give you two examples. First, consider the viceroy butterfly. For a long time, scientists thought the viceroy mimicked the monarch butterfly because monarchs are toxic to birds. However, recent research shows that viceroys are also distasteful themselves. So, the viceroy's resemblance to the monarch is not just about copying a warning signal; it's about reinforcing a shared warning. Both species benefit because predators learn to avoid that color pattern. Second, think about the harmless milk snake. It mimics the venomous coral snake with similar red, yellow, and black bands. But here's the twist: the milk snake's pattern is not exactly the same. It has a different sequence of colors. So, predators that have learned to avoid coral snakes might also avoid milk snakes, but the milk snake doesn't have to be perfect. The key point is that mimicry can serve different purposes, from sharing the cost of warning signals to gaining protection by imperfect imitation.