托福口语 Task 3

Niche Construction refers to the process by which organisms actively modify their environment, thereby altering the selective pressures they and other species face. Unlike natural selection, which acts on organisms passively, niche construction highlights the organism's role as an active agent in evolution. This modification can be physical, chemical, or biological, and its effects can persist across generations, influencing evolutionary pathways and ecological dynamics. The concept challenges traditional views by suggesting that organisms are not just products of their environment but also co-creators of it.

Professor: Let me give you a classic example. Consider beavers. When a beaver builds a dam across a stream, it creates a pond behind it. This pond changes the local environment dramatically—water slows down, sediment settles, and new plants grow. Now, these changes affect the beaver itself: the pond provides protection from predators and a stable place for its lodge, so beavers with better dam-building skills survive and reproduce more. Over time, the beaver population becomes even better at dam construction. But that's not all—other species, like fish and insects, also adapt to the pond. So, the beaver didn't just adapt to its environment; it actively shaped it, and that shaping influenced its own evolution and the evolution of others. This is a perfect illustration of niche construction.