托福口语 Task 3

In biology, the term 'mimicry' refers to the adaptive resemblance of one species to another, often for protection. A classic form is Batesian mimicry, where a harmless species evolves to imitate the warning signals of a dangerous or unpalatable species. Predators learn to avoid the harmful model, and consequently also avoid the harmless mimic. This increases the mimic's survival chances without the cost of producing toxins. The effectiveness depends on the mimic being less common than the model, so predators maintain their learned avoidance.

Professor: Let me give you a real example. Consider the scarlet king snake and the eastern coral snake. The coral snake is highly venomous with bright red, yellow, and black bands. The king snake is harmless but has a similar banding pattern. Young predators, like birds, first encounter a coral snake. They attack but get bitten or sick, and quickly learn to avoid any snake with those colors. Later, when they see a king snake, they hesitate and retreat, mistaking it for the dangerous coral. So the king snake survives because predators generalize the warning. Interestingly, in areas where coral snakes are rare, king snakes are attacked more often, which shows the mimicry only works when the model is common enough to teach predators. This perfectly illustrates the concept.