Ecological niche models and the geography of biological invasions: a review and a novel application - Invasive Plants: Ecological and Agricultural Aspects - page 40

presented in this chapter do highlight some of the limitations of using ENM to
predict biological invasions.
Reverse-ENM requires similar assumptions and suffers from analogous
limitations as Forward-ENM. The invaded range of a species is still likely to
be smaller than the geographic extent of its ecological niche, because the dis-
tributions of invaders are also subject to biotic influences and limitations to
dispersal. Also, for many potential case studies, we found it difficult to find
species for which requisite occurrence data existed for both the native and
invaded ranges. RIFA was an exception in this regard. Yet, as the RIFA case
study demonstrated, Reverse-ENM can be used i) to test for differences in the
constraints on the distribution of a species in its native and invaded ranges, and
ii) to gain insight into the mechanisms responsible for success of a particular
invasive species. Further study, with more species across different regions,
generally could determine whether or not the distributions of invaders are gov-
erned by the same factors in both their native and invaded ranges, or whether
RIFA is an isolated case.
Conclusion
There is an urgent need for a system that accurately can predict which species
are likely to become invasive and which regions are likely to be invaded. ENM
is a possible solution to predicting the potential geographic extent of biologi-
cal invasions. However, given the complexity of the invasion process and the
inability of ENM to incorporate fully the many factors that influence the dis-
tribution of species, ENM-based predictions should be interpreted as only a
first evaluation of regions potentially at risk of invasion, and not a prediction
of distribution per se .
Despite their threat to natural systems, invasive species are unparalleled
natural experiments and offer vast opportunity for ecological study. The
methodology described in this chapter, Reverse-ENM, attempts to make use
of these ongoing natural experiments. By comparing the native and invaded
distributions of species, Reverse-ENM can be used to develop hypotheses
concerning why invaders may succeed in their new environmental and geo-
graphic settings. Given the potential insights that can be obtained from such
assessments, it is surprising that there are not more studies that compare the
distributions of invasive species in both their native and invaded ranges.
However, Reverse-ENM has many of the same limitations as traditional
ENM, and the added difficulty of obtaining location data from both the native
and invaded ranges.
We used the red imported fire ant as an initial demonstration of Reverse-
ENM. By using the invaded distribution of the red imported fire ant to predict
its native range, we investigated two questions: 1) Do different factors con-
strain the native and invaded ranges of an invasive species? 2) If so, are the dif-
ferences meaningful at the macro-scales of analysis of ENM? Although