托福口语 Task 4

Today we're going to talk about a fascinating concept in biology called 'mimicry'. Mimicry occurs when one species evolves to resemble another species in order to gain a survival advantage. There are two main types we'll discuss. The first is Batesian mimicry, where a harmless species mimics a dangerous or toxic species to avoid predators. For example, the scarlet king snake, which is harmless, has evolved to look very similar to the deadly coral snake. Both have red, yellow, and black bands, but in the king snake, the red and yellow bands are separated by black, whereas in the coral snake, the red and yellow touch. Predators learn to avoid the coral snake, and they also avoid the king snake because of its resemblance. The second type is Müllerian mimicry, where two or more harmful species evolve to look alike, reinforcing avoidance learning among predators. Take the monarch and viceroy butterflies—both are distasteful to birds. When birds encounter a monarch, they learn to avoid it. Because the viceroy looks similar, birds will also avoid viceroys, even if they encounter them separately. This mutual resemblance benefits both species by reducing the number of individual butterflies killed during predator learning.