托福口语 Task 4

Today, I want to talk about a fascinating concept in biology called 'mimicry.' Mimicry is when one species evolves to look or behave like another species, often to gain a survival advantage. There are two main types of mimicry: Batesian and Müllerian. Let me give you two examples to clarify. First, consider the harmless king snake. It has evolved to resemble the venomous coral snake, with similar red, yellow, and black bands. Predators that have learned to avoid the coral snake also avoid the king snake, even though the king snake is not dangerous. This is Batesian mimicry, where a harmless species mimics a harmful one. Second, think about two species of poisonous butterflies, the monarch and the viceroy. Actually, the viceroy was once thought to be harmless and mimicking the monarch, but recent research shows that the viceroy is also distasteful to birds. So both species share similar warning colors, and predators quickly learn to avoid both. This is Müllerian mimicry, where two harmful species mimic each other, reinforcing the warning signal. So, the main point is that mimicry can evolve in different ways, depending on the species' own defenses.