You shouldn’t judge a book by its cover. And you shouldn’t judge a species by its place of origin. So say ecologists in a commentary in the journal Nature. [Mark Davis et al, Don't judge species on their origins] They argue that conservationists should assess organisms based on their impact on the local environment, rather than simply whether they’re native.

When you hear the phrase “non-native species” you no doubt conjure up an image of an invasive animal or plant that’s pushing out the native species and wreaking havoc on the local ecology—like zebra mussels in the Great Lakes or cane toads in Australia. But Mark Davis of Macalester College in Minnesota and his colleagues see things differently. They say that being indigenous doesn’t grant a species special rights to inhabit an ecosystem. Or mean that its presence is good for the environment. The insect currently thought to kill more trees than any other in America is the native mountain pine beetle. And many invaders actually boost biodiversity, not decimate it.

As climate change and urbanization continue to reshape the ecological landscape, more species will leave their homelands—making the distinction between resident and alien a moot point. So, ask not where a species comes from. But whether it belongs.

—Karen Hopkin

[The above text is an exact transcript of this podcast.]

[Scientific American is part of the Nature Publishing Group.]