托福口语 Task 4

Today, we're going to talk about a fascinating concept in animal behavior called 'sensory exploitation.' This idea suggests that in some species, a male's courtship signal evolves to exploit a pre-existing sensory bias in the female, which originally had nothing to do with mating. In other words, the female's brain is already wired to respond to a certain stimulus for another reason, and the male's display taps into that. Let me give you two examples. First, consider the water mite. Female water mites are predators that detect prey by sensing vibrations in the water. Males have evolved to produce vibrations that mimic those of the female's prey, so when a female senses these vibrations, she approaches, expecting a meal, but instead finds a mate. Second, there's a species of fish called the swordtail fish. Females have a natural preference for larger body size, because larger males are often healthier and better territory holders. However, males have evolved a long sword-like extension on their tail fin that makes them appear larger than they actually are. When females see a male with a longer sword, they are more attracted, even though the sword itself doesn't indicate health. So in both cases, the males exploit sensory systems that females already use for other purposes.