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 a male animal evolves a trait that appeals to a pre-existing sensory bias in the female, not because the trait signals quality, but simply because it triggers a response that females already have. Let me give you two examples. First, consider the swordtail fish. Female swordtails have a natural preference for longer tails, even in species where males don't have them. Scientists discovered this by testing females with artificial models—they preferred longer tails regardless of the species. So, when a male swordtail evolved a long sword-like extension, it exploited that existing preference. Second, think about the tungara frog. Females are attracted to the 'chuck' sound in male calls, because it resembles the sound of raindrops hitting water—a sound that signals a good breeding environment. Males that add chucks to their calls are more successful, even though the chucks don't indicate better health. So, in both cases, the male's trait works because it taps into a pre-existing sensory bias in the female.