托福口语 Task 4

Today, we're going to talk about a fascinating concept in animal behavior called 'sensory exploitation.' This is when animals evolve traits that exploit the pre-existing sensory biases of other animals, often to attract mates or gain a survival advantage. The key idea is that these traits didn't evolve because they were originally adaptive, but because they happen to trigger a response that already exists in the receiver's brain. Let me give you two examples. First, consider the male túngara frog. Females are naturally attracted to low-frequency sounds, which in their ancestors signaled a large predator—so they'd move away. But males now produce a low-frequency 'chuck' as part of their call. This sound exploits that ancient fear response, but now it attracts females because they associate it with a robust male. Second, think about the guppy fish. Female guppies have an innate preference for orange spots—this may have evolved because orange resembles ripe fruit, a food source. Male guppies have evolved bright orange spots to exploit this bias, making them more attractive to females. In both cases, the traits didn't arise from a need to signal quality; they simply hijacked existing sensory preferences.