Nativeness as Gradient: Towards a More Complete Value Assessment of Species in a Rapidly Changing World

Conservation biologists recognize a duty to maintain as much value as possible in ecosystems that are threatened by recent anthropogenic impacts. Until recently the paradigm of contemporary conservation seemed relatively straightforward: the best way to maintain the value of species and ecosystems at a given location was to maintain—or shepherd the system back towards—historical conditions. Among the most difficult theoretical tasks was the determination of “baseline” historical conditions (or trajectories) to return to, recognizing the dynamism of ecosystems over time. However, the rate, scale, and magnitude of contemporary climate change, species introductions, and land-use change make it increasingly impractical to return locations to any kind of historical state. This forces a paradigm shift which is both ongoing and difficult, and necessitates a rigorous evaluation of the scientific and ethical foundations of modern conservation along with a careful reexamination of terminology. Here, I discuss the moral relevance and waning utility of the geographically-based and dichotomous understanding of “native” (or “in situ”) which is an important component of conservation ethics and practice. I then propose a new understanding of nativeness in which a species is native—not to a geographic location—but to a quantifiable set of biotic, climatic, geologic, and topographic conditions (i.e. its niche) that can then map to geographic space. Following this, I demonstrate the unique utility of this concept, which I will refer to as “econativeness,” in thinking through conservation problems—range expansions, range contractions, species introductions, and assisted migration—where the classical understanding of nativeness has become increasingly inadequate for assessing the moral value of species.