托福口语 Task 3

Niche Construction refers to the process by which organisms actively modify their environment, which in turn alters the selection pressures on themselves and other species. Unlike passive adaptation, niche construction highlights the organism's role as an ecological engineer, creating changes that can affect survival and reproduction. This concept challenges the traditional view that evolution is solely a response to external environmental changes, emphasizing instead a feedback loop between organisms and their habitats.

Professor: Let me give you an example. Beavers are a classic case of niche construction. They build dams across streams, creating ponds. This changes the local environment dramatically—water flow slows, sediment accumulates, and new plants grow. Now, these changes affect the beavers themselves. The pond provides them with protection from predators and easy access to food during winter, because they can swim under the ice to reach their stored branches. Over time, this constructed pond also influences other species, like fish and birds, but for the beaver, the dam and pond increase their survival and reproductive success. So, the beaver isn't just adapting to a given environment; it's building a new one that shapes its own evolution and that of the ecosystem around it.