Relative roles of climatic suitability and anthropogenic influence in determining the pattern of spread in a global invader

What is it about?

A major goal in ecology is to develop predictive models to determine which invasive species may become widespread and where they may invade. This study is unusual because it compares the relative importance of four different factors that might promote colonisation by an invasive species. The four factors are: climatic suitability, biotic resistance by native taxa, human-aided dispersal, and human modification of habitats, and the case study species is one of the world's most notorious invasive species, the Argentine ant (Linepithema humile). Climatic suitability and the extent of human modification of habitats were primarily responsible for the distribution of this global invader. However, we also found some evidence for biotic resistance by native communities. Somewhat surprisingly, and despite the often cited importance of propagule pressure as a crucial driver of invasions, metrics of the magnitude of international traded commodities among countries were not related to global distribution patterns. Our analyses provide strong evidence for the interplay of abiotic and biotic determinants of spread (i.e. abiotic = the physical environemnt and biotic = the diversity and composition of the resident community). The relatively limited contribution of trade highlights the challenges of limiting the spread and subsequent impact of highly invasive species into human-modified environments of suitable climate.

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Why is it important?

Invasive species are one of the leading causes of modern-day extinctions. They can also be responsible for large economic losses to agriculture and forestry. The method followed in this paper provides insights into which factors limit/promote the spread of invasive species.