A neutral terminology to define ‘invasive’ species

Abstract

The use of simple terms to articulate ecological concepts can confuse ideological debates and undermine management efforts. This problem is particularly acute in studies of nonindigenous species, which alternatively have been called ‘exotic’, ‘introduced’, ‘invasive’ and ‘naturalised’, among others. Attempts to redefine commonly used terminology have proven difficult because authors are often partial to particular definitions. In an attempt to form a consensus on invasion terminology, we synthesize an invasional framework based on current models that break the invasion process into a series of consecutive, obligatory stages. Unlike previous efforts, we propose a neutral terminology based on this framework. This ‘stage‐based’ terminology can be used to supplement terms with ambiguous meanings (e.g. invasive, introduced, naturalized, weedy, etc.), and thereby improve clarity of future studies. This approach is based on the concept of ‘propagule pressure’ and has the additional benefit of identifying factors affecting the success of species at each stage. Under this framework, invasions can be more objectively understood as biogeographical, rather than taxonomic, phenomena; and author preferences in the use of existing terminology can be addressed. An example of this recommended protocol might be: ‘We examined distribution data to contrast the characteristics of invasive species (stages IVa and V) and noninvasive species (stages III and IVb)’.

Conceptual Frameworks and Methods for Advancing Invasion Ecology

“…Some recent studies offer ideas for a synthesis of invasion theory (Colautti and MacIsaac 2004;Blumenthal 2006;Catford et al 2009;Davis 2009;Gurevitch et al 2011). These approaches each put together different pieces of available knowledge in a specific and valuable way, but each approach is limited in what it covers.…”

How to Achieve Effectiveness in Problem-Oriented Landscape Research: The Example of Research on Biotic Invasions

“…Further, some experts reserve the term "invasive" only for those species that are perceived to have negative economic or ecological impacts. Given these two dimensions, spreading species that are either only alien, or native and alien species, and that either pose a perceived problem or not, may be called invasive (for an extensive discussion of the terminology see Colautti and McIsaac, 2004;Daehler, 2001;Richardson et al, 2000). The different meanings of the terms reflect the dynamics of the research field that are discussed in this article.…”

“…Nevertheless, given the weak predictability of the impacts of individual alien species, a precautionary approach has been proposed for invasive species risk assessment systems, which is based on the assumption that an alien species is problematic until proven otherwise (Simberloff, 2005;Wittenberg and Cock, 2001). Thus, the ongoing discussion among biologists, social scientists and philosophers on an appropriate use of the native/alien distinction as a proxy for understanding and predicting impacts of invasive species (Brown and Sax, 2004;Colautti and McIsaac, 2004;Kendle and Rose, 2000;Lodge and Shrader-Frechette, 2003;Shrader-Frechette, 2001) cannot easily be dismissed.…”

Metaphors in Invasion Biology: Implications for Risk Assessment and Management of Non-Native Species

“…It has come to a point where critics are advocating for the 'end of invasion biology' based on its perceived xenophobic stance, the ambiguity of definitions, and lack of foundation as such (Valéry, Fritz, & Lefeuvre, 2013). Several authors have proposed a more objective approach and neutral terminology to describe invasive species (Brown & Sax, 2004;Colautti & MacIsaac, 2004). In response to these proposals, others claim that this mode of non-action of scientists is inconsistent with their conservation values (Larson, 2007;Young & Larson, 2011) or may even hamper the development of ecological knowledge which benefits from a wealth of terms and meanings (Hodges, 2008).…”