Ecological niche models and the geography of biological invasions: a review and a novel application - Invasive Plants: Ecological and Agricultural Aspects - page 27

Ecological niche models and the geography of
biological invasions: a review and a novel
application
Matthew C. Fitzpatrick and Jake F. Weltzin
Department of Ecology and Evolutionary Biology, 569 Dabney Hall, University of Tennessee,
Knoxville, TN 37996-1610, USA
Introduction
Invasive species are a threat to Earth's natural ecological systems [1], and
increasing global commerce likely will intensify the problem by transporting
greater numbers of potential invaders between regions. Preventing the intro-
duction and establishment of invasive species is generally a better strategy than
eradication, but to prevent invasions effectively, managers must have a priori
knowledge of which species are likely to become invasive and which regions
are likely to be invaded. Given their high economic and ecological costs, there
is an urgent need for a system that accurately can predict invasions. However,
despite decades of effort, the desire to develop invasion biology into a truly
predictive science remains unrealized [2].
Generally, biologists have used two approaches to predict the invasive
potential of species: 1) examination of intrinsic traits, such as life history
(e.g., [3]), and 2) analysis of extrinsic factors, such as the environment in
which a species exists (e.g., [4, 5]). Within this latter category is ecological
niche modeling (ENM), the focus of this chapter. ENM attempts to identify
areas prone to invasion by evaluating the degree of environmental similarity
between the native and potential ranges of an invader. The first step in this
process is the development of a model that relates the current geographic dis-
tribution of a species to the environmental conditions within the occupied
region. Once developed, the model can be used to identify potentially suitable
habitats in other regions.
Typically, ecological niche models consider only the abiotic environment.
Thus, this approach is often criticized because both the native and invaded
distributions of species also are influenced by biotic factors, such as interac-
tions with other organisms [6, 7]. In addition, limitations to dispersal can pre-
vent a species from occupying all suitable habitats. Therefore, the geograph-
ic distribution of a species may not be indicative of the full range of environ-
mental conditions it can tolerate. Furthermore, both species and their ranges