Opinion The “Non-Native” Enigma

Non-native species have been introduced to ecosystems throughout the world, and in some instances, have degraded the invaded system. Consequently, the distinction between native and non-native species has become an integral component of conservation planning. Recently however, the conservation value of the distinction has been questioned. We examine how the native versus non-native dichotomy is intrinsically ambiguous, which therefore limits the conservation utility of the designation in and of itself. A large degree of uncertainty exists as to whether many species are or are not native. Measures outside the non-native dichotomy (e.g., impacts, evolutionary ecology, paleontology) could better inform conservation efforts, because species’ ranges are part of dynamic processes. We recommend that the � eld of conservation should avoid arbitrary points in history as benchmarks and incorporate findings from multiple disciplines to better manage resources.