But scientists think it's now what's called an exaptation—a trait evolved for one purpose but now serves a different one.

这种现象目前被科学家们称为功能变异——意思是因一个目的进化出的特性，但是后来实现了另一个目的。

Well, feathers are a great example of an exaptation.

好吧，羽毛是扩展的一个很好的例子。