Summary: OIKOS 98: 316, 2002
Using niche-based GIS modeling to test geographic predictions of
competitive exclusion and competitive release in South American
Robert P. Anderson, A. Townsend Peterson and Marcela Go´mez-Laverde
Anderson, R. P., Peterson, A. T. and Go´mez-Laverde, M. 2002. Using niche-based
GIS modeling to test geographic predictions of competitive exclusion and competitive
release in South American pocket mice. Oikos 98: 316.
Geographic studies addressing the role of competition in determining species'
macrodistributions have been limited by only simple or subjective means of identify-
ing regions of suitable habitat. Now, ecological-niche models of species' potential
distributions present a possible approach to testing for the geographic patterns
predicted under competitive exclusion and competitive release. Previously, we mod-
eled the potential distributions of two spiny pocket mice (Heteromys australis and H.
anomalus) in northwestern South America using specimen localities, environmental
data, and the Genetic Algorithm for Rule-Set Prediction (GARP). Here we superim-
pose the models to examine known distributional records in areas of potential
sympatry between the two species, thus testing the geographic predictions of compet-
itive exclusion. In addition, we examine environmental characteristics of known
localities, testing for data consistent with competitive release. Areas of potential