Glossary of Non-Native Ant Terminology
Decades of papers on "exotic," "alien," "adventive," "invasive," "tramp," "non-native," "introduced," and "non-indigenous" and "colonizing" ants have resulted in a confusing nomenclatural problem. We all have our own idea of what these terms mean. Below, I provide succinct definitions for what I think the terms should be used (McGlynn 1999), in a manner similar to other ecologists specializing in ecological invasions (Williamson and Fitter 1996). These definitions also are consistent with the definitions of the United States Executive Order on Invasive Species 1999-02-03.
Non-native: A species which is established outside its native habitat. With respect to ants, ants with an established reproducing colony.
Exotic: Same as non-native
Introduced: Same as non-native
Non-indigenous: Same as non-native
Alien: Same as non-native
Adventive: Located outside habitat, though an reproductive population may not be established
Transferred: Collected outside native habitat, without knowledge of established nests
Transported: Same as transferred; often refers to animals found in quarantine inspection
Invasive: A species which is spreading its geographic range into niches occupied by other species. Documentation of an invasive species requires an ecological study to demonstrate the displacement of other ants.
Tramp: An widespread ant species spread by human commerce with a specific syndrome of life history characteristics: extreme polygyny, unicolonial or highly polydomous nest structure, and colony reproduction by budding (sensu Passera 1994)
Colonizing: An ant species which is successful at creating nests in new areas. While some exotic ants are successful colonizers, many colonizing species are not exotic -- and many exotics are not colonizers.
Native: These definitions do not necessarily define where a species is native. How do I define where a species is native? Sometimes the non-native status of a species is clear from previous collections and existing knowledge from biogeography and systematics. Other times, boundaries are a lot blurrier. Is a species non-native if it has been there for 400 years? Where I (personally) draw the line is whether the species was introduced by human activity, or whether it got there entirely on its own. This is an admittedly arbitrary line, and in some cases we won't know what the original native habitat was. Ultimately this academic fussing doesn't matter much for conservation planning, as the spread of non-natives into new areas is more clear-cut.
McGlynn, T.P. 1999. The biogeography, behavior, and ecology of exotic ants. Ph.D. Dissertation, University of Colorado, Boulder, CO, USA.
Passera, L. 1994. Characteristics of tramp ants. Pages 23-43 in D. Williams, editor. Exotic Ants. Westview Press, Boulder, Colorado, USA.
Williamson, M., and Fitter, A. 1996. The varying success of invaders. Ecology 77: 1661-1666.
created: 9 July 1999 last updated: 3 May 2000