Revisiting the use of the invasive species concept: An empirical approach

Abstract

Invasion science has not been developed without controversies. Two questions that are still unsolved are: what is an invasive species?, and are invasive species an inherent conservation problem? These questions have led to discussions about effects versus origins. In contrast to the definitional problems, a unified framework describing invasion as a step-by-step process has been widely accepted. I conducted a bibliographic search with two separate databases searching for (i) evidence of less use of controversial terms over time; (ii) how many articles defined 'invasive species'; (iii) the criteria used to define a species as invasive; and (iv) in which stage of the invasion continuum were species labelled as invasive located. My results show that controversial terms are widely used, that authors rarely define 'invasive species' and, often, it is very complicated to determine which criterion they used. In addition, only a fraction of the species labelled as invasive could be classified as such according to the unified framework of invasion stages. This is not a merely semantic issue, because invasive is a strong and value-laden term that is used to guide environmental agendas. The uncritical use of a key concept could hamper research, complicate communication among peers and produce mixed results.

Rethinking the native range concept

“…Although there is no compelling argument that every region of the world should use the same temporal baseline to determine nativeness, one should be aware that when comparing native species between regions one could be applying different time frames to determining nativeness. Kull (2018) mentioned that some confusion arises when using "invasive" in different data sets because several definitions of invasive species exist (Blackburn et al 2011;Pereyra 2016); the same could be said for native species.…”

Invasive species denialism: Sorting out facts, beliefs, and definitions

“…Both situations occur in the literature on biological introductions, but emphasis on the impacts of NIS, and particularly of those that are perceived as negative, seems more common than their denial, and NIS are often unduly maligned (Brown & Sax, 2004;Humair et al, 2014;Pereyra, 2016). This bias often takes the form of covert hints in the interpretations and discussions of experimental or observational data that show no relationship between origin and impact.…”

“…Attempts at unifying terminology used in research on introduced species (Colautti & MacIsaac, 2004;Davis, 2009;Richardson et al, 2000;Russell & Blackburn, 2017a) have had very limited success (Sagoff, 2018) and explicit opposition (Hodges, 2008;Larson, 2007). Despite (or because of) its value-laden implications, the term "invasive" has been growing in acceptance (Pereyra, 2016), to the point that the field itself is usually referred to as "invasion biology," even by scholars opposed to the concept that all NIS are harmful (Davis, 2009). "Invasive" is a valueladen adjective, with unsubtle negative connotations (Davis, 2009;Russell & Blackburn, 2017b), and the notion of "negative" has been incorporated by researchers and international organizations in their definition of "invasive" (IUCN, 2018;Russell & Blackburn, 2017a, b;Simberloff et al, 2012;WWF, 2018).…”

Does rainbow trout justify its high rank among alien invasive species? Insights from a nationwide survey in Greece

“…An answer to these questions requires an understanding of what is meant by the term ‘invasive alien species’. Several definitions have been proposed (reviewed by Heger et al, ; Pereyra, ), but two groups of definitions prevail in scientific literature: the ‘ecological definitions’ and the ‘policy definitions’ (Heink, Van Herzele, Bela, Kalóczkai, & Jax, ). Both groups include establishment and spread as necessary criteria of invasiveness but differ over whether ecological or other impacts (e.g.…”