Accessible areas in ecological niche comparisons of invasive species: Recognized but still overlooked

Huijie Qiao,Luis E Escobar,A Townsend Peterson

doi:10.1038/s41598-017-01313-2

Huijie Qiao, Luis E Escobar + Show 1 more

Open Access

https://doi.org/10.1038/s41598-017-01313-2

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Abstract

Understanding biological invasions is crucial for their control and prevention. Specially, establishing whether invasive species operate within the constraint of conservative ecological niches, or if niche shifts occur at all commonly as part of the invasion process, is indispensable to identifying and anticipating potential areas of invasion. Ecological niche modeling (ENM) has been used to address such questions, but improvements and debate in study design, model evaluation, and methods are still needed to mature this field. We reanalyze data for Gray Squirrels (Sciurus carolinensis), native to North America, but invasive in Europe. Our main finding was that, when the analysis extent is established carefully based on analogous sets of environmental conditions, all evidence of niche shifts disappears, suggesting that previous reports of niche shifts for this species are artifacts of methods and interpretation, rather than biological reality. Niche conservatism should be tested only within appropriate, similar, environmental spaces that are accessible to both species or populations being compared, thus avoiding model extrapolation related to model transfers. Testing for environmental similarity between native and invaded areas is critical to identifying niche shifts during species invasion robustly, but also in applications of ENM to understanding temporal dimensions of niche dynamics.

Highlights

Understanding biological invasions is crucial for their control and prevention
In light of recent demonstrations of dramatic, biologically unrealistic extrapolation that occurs in transferring niche models from M to broader areas[28], we propose that quantification and testing of niche shifts should be done only within the set of environments overlapping between the populations in native and invaded areas (Fig. 1)
We explored environmental characteristics of each study area, and found that the environmental conditions corresponding to invaded areas in the British Islands were completely contained within the native-range environments (Supplementary Material S1), at least with respect to the first three principal components

Summary

Introduction

Understanding biological invasions is crucial for their control and prevention. Specially, establishing whether invasive species operate within the constraint of conservative ecological niches, or if niche shifts occur at all commonly as part of the invasion process, is indispensable to identifying and anticipating potential areas of invasion. Testing for environmental similarity between native and invaded areas is critical to identifying niche shifts during species invasion robustly, and in applications of ENM to understanding temporal dimensions of niche dynamics. Several recent papers on species invasions have concluded that niches have shifted when available evidence suggests use of novel environments by invasive species in the invaded range[8, 17, 20, 21], when those conditions could be unavailable or inaccessible in the native range[22,23,24]. We note that this debate is not just a technical detail: if niches shift during species’ invasions, predicting the geographic potential of invasive species will be much more difficult

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