From introduction to equilibrium: reconstructing the invasive pathways of the Argentine ant in a Mediterranean region

Abstract

Determining the geographical range of invasive species is an important component of formulating effective management strategies. In the absence of detailed distributional data, species distribution models can provide estimates of an invasion range and increase our understanding of the ecological processes acting at various spatial scales. We used two complementary approaches to evaluate the influence of historical and environmental factors in shaping the distribution of the Argentine ant (Linepithema humile), a widespread, highly invasive species native to South America. Occurrence data were combined with environmental data at incremental spatial scales (extent and resolution) to predict the suitable range of the ant invasion using ecological niche models. In addition, we also used a spread model that simulated the jump dispersal of the species to identify the most plausible scenarios of arrival of L. humile in the NE Iberian Peninsula at local scales. Based on the results of both modelling practices, we suggest that L. humile might have reached its maximum geographic range at regional scales in the NE Iberian Peninsula. However, the species does not appear in equilibrium with the environment at small spatial scales, and further expansions are expected along coastal and inland localities of the Costa Brava. Long-distance jumps are ultimately responsible for the spread of the Argentine ant in the area. Overall, our study shows the utility of combining niche based models with spread models to understand the dynamics of species' invasions.

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

“…42) for the expansion of the Argentine ant at regional and local scales, not only among countries, is needed to assess the geographic dimensions of the invasion over time in fine detail. This type of information is crucial to anticipate the rate at which Argentine ants will spread and the areas most likely to be invaded (28,43). Finer-resolution data on patterns of commerce, which incorporate a strong historical perspective, are needed to provide a more rigorous test of the role of propagule pressure at global scales.…”

Modelling Spread in Invasion Ecology: A Synthesis

“…By the end of 1970s, when computers became widely available, research on CAs accelerated rapidly. In invasion ecology, the spread of invasive species is often simulated by CAs (often called lattice models) with continuous cell state on heterogeneous landscapes (Roura -Pascual et al 2009a ).…”

“…In practice, the spatial version of the model should be used and has been applied to reconstruct the spread of Argentine ants in Spain (Roura -Pascual et al 2009a ). One proposition from this model that has not been tested in invasion ecology is that, all else being equal, species with large potential distributions spread faster than those with small potential range.…”

Elton's insights into the ecology of ant invasions: lessons learned and lessons still to be learned

“…In general, environmental niche models suggest that the Argentine ant has the potential for further spread into central Madagascar, Taiwan, southeast Asia, high -elevation Ethiopia and Yemen, and numerous oceanic islands are likely at risk of future establishment (Roura -Pascual et al 2004 ;Hartley et al 2006 ). Environmental niche modelling can be an important tool for conservation practitioners, but they could be improved by incorporating information on dispersal (see, for example, Roura -Pascual et al 2009 ) and ecological interactions with other species, as well as evolutionary responses to changing climates (Fitzpatrick et al 2007 ). For example, the outcome of interactions between Argentine ants and native species can depend on environmental temperature (Holway et al 2002b ), but understanding how climatic change will modify interspecifi c interactions, drive evolutionary responses of both native and invasive species, and ultimately mediate the impact of invasive species is a pressing challenge (Dukes & Mooney 1999 ;Arauj ó & Rahbek 2006 ).…”