托福口语 Task 4

Today we're going to talk about a fascinating concept in animal behavior known as 'sensory exploitation.' This is when a species evolves a particular trait not because it directly helps survival, but because it exploits a pre-existing sensory bias in another species, often a mate or a predator. To illustrate, consider two examples from the animal kingdom. First, the male túngara frog. Females have an innate preference for low-frequency calls because these sounds are naturally associated with larger predators, which they instinctively avoid. However, male frogs have evolved to produce a 'chuck' at the end of their call, which is a low-frequency component that females find irresistible—even though it actually makes the male more vulnerable to predators like bats. Second, consider the guppy. Female guppies are naturally attracted to orange spots, likely because orange signals ripe fruit in their environment. Over time, male guppies have developed vivid orange spots on their bodies, which females choose as mates. These spots don't indicate health or genetic quality; they simply exploit the females' pre-existing visual bias.