托福口语 Task 3

In biology, organisms often exhibit behavioral adaptations that enhance their survival. One such adaptation is 'mimicry', where a species evolves to resemble another species or an object in its environment. Mimicry can be deceptive, helping the mimic avoid predators or sneak up on prey. There are two main types: Batesian mimicry, where a harmless species imitates a dangerous one, and Müllerian mimicry, where two harmful species resemble each other. The key is that the resemblance provides a survival advantage, often by tricking predators or prey.

Professor: Let me give you a clear example of Batesian mimicry from a study in the Amazon. There's a harmless species of butterfly called the 'viceroy' that mimics the 'monarch' butterfly, which is toxic to birds. Monarchs store toxins from the milkweed they eat as caterpillars, making them taste terrible and causing birds to vomit. Birds quickly learn to avoid monarchs after one bad experience. Now, the viceroy doesn't have those toxins, but it has evolved wing patterns and colors almost identical to the monarch. So when a young bird spots a viceroy, it mistakes it for a monarch and leaves it alone, remembering the earlier unpleasant encounter with the monarch. This way, the viceroy avoids being eaten without having any chemical defense of its own. The resemblance isn't perfect, but it's close enough to fool the bird's memory. This dramatically increases the viceroy's survival rate in areas where monarchs are common.