title: Evidence of niche shift and global invasion potential of the Tawny Crazy ant, Nylanderia fulva.
abstract: Analysis of an invasive species' niche shift between native and introduced ranges, along with potential distribution maps, can provide valuable information about its invasive potential. The tawny crazy ant, Nylanderia fulva, is a rapidly emerging and economically important invasive species in the southern United States. It is originally from east-central South America and has also invaded Colombia and the Caribbean Islands. Our objectives were to generate a global potential distribution map for N. fulva, identify important climatic drivers associated with its current distribution, and test whether N. fulva's realized climatic niche has shifted across its invasive range. We used MaxEnt niche model to map the potential distribution of N. fulva using its native and invaded range occurrences and climatic variables. We used principal component analysis methods for investigating potential shifts in the realized climatic niche of N. fulva during invasion. We found strong evidence for a shift in the realized climatic niche of N. fulva across its invasive range. Our models predicted potentially suitable habitat for N. fulva in the United States and other parts of the world. Our analyses suggest that the majority of observed occurrences of N. fulva in the United States represent stabilizing populations. Mean diurnal range in temperature, degree days at ≥10°C, and precipitation of driest quarter were the most important variables associated with N. fulva distribution. The climatic niche expansion demonstrated in our study may suggest significant plasticity in the ability of N. fulva to survive in areas with diverse temperature ranges shown by its tolerance for environmental conditions in the southern United States, Caribbean Islands, and Colombia. The risk maps produced in this study can be useful in preventing N. fulva's future spread, and in managing and monitoring currently infested areas.
authors.affiliation: Natural Resource Ecology Laboratory Colorado State University Fort Collins Colorado 80523-1499 ; Department of Ecosystem Science and Sustainability Colorado State University Fort Collins Colorado 80523-1499.
authors.forename: Sunil
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Brackenridge Field Laboratory Section of Integrative Biology University of Texas at Austin 2907 Lake Austin Blvd Austin Texas 78703.
authors.forename: Edward G
authors.initials: EG
authors.lastname: LeBrun
authors.affiliation: Natural Resource Ecology Laboratory Colorado State University Fort Collins Colorado 80523-1499 ; Department of Ecosystem Science and Sustainability Colorado State University Fort Collins Colorado 80523-1499.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Stohlgren
authors.affiliation: Natural Resource Ecology Laboratory Colorado State University Fort Collins Colorado 80523-1499.
authors.forename: Jared A
authors.initials: JA
authors.lastname: Stabach
authors.affiliation: Texas Research Institute for Environmental Studies Sam Houston State University Huntsville Texas 77341-2506.
authors.forename: Danny L
authors.initials: DL
authors.lastname: McDonald
authors.affiliation: USDA-ARS Center for Medical, Agricultural & Veterinary Entomology Gainesville Florida 32608-1067.
authors.forename: David H
authors.initials: DH
authors.lastname: Oi
authors.affiliation: Department of Biological Sciences Towson University Towson Maryland 21252-0001.
authors.forename: John S
authors.initials: JS
authors.lastname: LaPolla
keywords: Biological invasions; MaxEnt; biotic homogenization; ecological niche models; invasion stages; niche expansion; risk analysis; species distribution modeling