Just as you can’t judge a book by its cover, you shouldn’t judge a species principally by its origin—that is, whether it’s a native or non-native, says ecologist Scott Carroll of the University of California, Davis.

However, the native-vs.-non-native species distinction appears to be the “guiding principle” in today’s conservation and restoration management, say Carroll and 18 other worldwide ecologists who co-authored the newly published essay, “Don’t Judge Species on Their Origins”  in the journal Nature.

“Nativeness is not a sign of evolutionary fitness or of a species having positive effects,” wrote the ecologists, led by senior author Mark Davis, a biology professor at Macalester College, St. Paul, Minn.

Among the non-natives mentioned in the Nature essay are pheasants, honeysuckle and tamarisk. (Non-natives also include the honey bee, introduced in the United States in 1620 by European colonists.)

Part of the essay is based on Carroll’s concept of conciliation biology, an integrated approach that he recently introduced for the management of biological systems (environmental, agricultural, natural resource, public health, and medical systems) incorporating non-native species.

Carroll, an ecologist in professor Sharon Lawler’s lab, UC Davis Department of Entomology, and the founding director of the Davis-based Institute for Contemporary Evolution, said he “supports the work of conservation biology to protect natural ecosystems from invasive alien species. But we need to simultaneously consider the costs of that effort. Eradication programs often fail, and can do more harm than good, especially when non-native species become integrated into their new communities.”

“Global change alters conditions for all species, and from a practical perspective, origin can be only one of many criteria we consider,” said Carroll, who received his doctorate in biology from the University of Utah. “Appraising non-native organisms more openly invites us to more seriously contemplate our aims when managing novel communities of mixed origin.”

According to the Nature essay, non-natives are so vilified today that a “pervasive bias” exists against non-native species, a bias embraced by “the public, conservationists, and managers and policy-makers, as well by as many scientists, throughout the world.”

English botanist John Henslow first outlined the concept of nativeness in 1835. British ecologist Charles Elton wrote about invasion biology in his 1958 book,The Ecology of Invasions by Animals and Plants. Invasion biology became a discipline in the 1990s.

The Nature essay authors  point out that some non-native species are indeed troubling. The Zebra mussels (Dreissena polymorpha) has cost the U.S. power industry and water utilities hundreds of millions. Avian malaria killed off half of Hawaii’s native bird species.