"Not all exotic species are invasive. Origin of the species isn't the issue; behavior is. And though the language some use to describe invasive species is redolent with horrible memory, that doesn't mean we ought to fall into the trap of metaphor. People coming from other places increase diversity, while invasive species decrease it."And he offers a tidy one-liner regarding the "balance of nature":
"Nature no more 'seeks balance' than a slinky seeks the stair tread on which it happens to stop."