Biological invasions and natural colonisations: are they that different?

Abstract

We argue that human-mediated invasions are part of the spectrum of species movements, not a unique phenomenon, because species self-dispersing into novel environments are subject to the same barriers of survival, reproduction, dispersal and further range expansion as those assisted by people. Species changing their distributions by human-mediated and non-human mediated modes should be of identical scientific interest to invasion ecology and ecology. Distinctions between human-mediated invasions and natural colonisations are very valid for management and policy, but we argue that these are value-laden distinctions and not necessarily an appropriate division for science, which instead should focus on distinctions based on processes and mechanisms. We propose an all-encompassing framework of species range expansion. This does not detract from the importance of invasion biology as a discipline, but instead will help bring together research being conducted on multiple taxa, and by multiple disciplines, including epidemiology, that are often focused on an identical phenomenon: colonisation.

Biological invasions and natural colonisations are different – the need for invasion science

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AbstractIn a recent Discussion Paper, Hoffmann and Courchamp (2016) posed the question: are biological invasions and natural colonisations that different? This apparently simple question resonates at the core of the biological study of human-induced global change, and we strongly believe that the answer is yes: biological invasions and natural colonisations differ in processes and mechanisms in ways that are crucial for science, management, and policy.

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“…Something in the way they move Hoffmann and Courchamp (2016) argue that human-mediated extra-range dispersal does not differ in terms of processes or mechanisms from natural colonisation, but that all dispersal events sit on a broad but continuous spectrum of species movements. Their rationale is that in both human-mediated extra-range dispersal and natural colonisations, populations have to overcome the same barriers (survival, reproduction, dispersal and further range expansion), and differ only in the "inconsequential" way in which they move from the original to the novel recipient locations (using their own means versus human transportation).…”

“…Their rationale is that in both human-mediated extra-range dispersal and natural colonisations, populations have to overcome the same barriers (survival, reproduction, dispersal and further range expansion), and differ only in the "inconsequential" way in which they move from the original to the novel recipient locations (using their own means versus human transportation). Hoffmann and Courchamp (2016) suggest that there are four main reasons why scientists traditionally consider human-mediated extra-range dispersal and natural colonisations separately: (i) propagule pressure is greater for human-mediated extra-range dispersal; (ii) colonisation pressure is greater for human-mediated extra-range dispersal; (iii) genetic diversity is different; and (iv) human-mediated extra-range dispersal is more likely to result in invasions which lead to mass extinctions. They then argue that these differences are not clear-cut, and that even if such differences exist, they are differences of degree (e.g.…”

When similarities matter more than differences: a reply to Wilson et al.

“…In our recent paper (Hoffmann and Courchamp 2016) we point out at that despite many obvious differences between human-mediated biological invasions and natural colonisation, there are also many similarities. Ultimately, yes, they have differences, no one denies that, but are they THAT different?…”

Seven years of NeoBiota – the times, were they a changin’?

“…We therefore always welcome papers raising scientific discourse. One of the most controversial papers probably was that of Hoffmann and Courchamp (2016). The authors argued that human-mediated invasions are part of the spectrum of species movements, not a unique phenomenon, because species selfdispersing into novel environments are subject to the same barriers of survival, reproduction, dispersal and further range expansion as those assisted by people.…”