Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-29T15:21:17.213Z Has data issue: false hasContentIssue false
  • English
  • Français

Dislocation from coevolved relationships: a unifying theory for plant invasion and naturalization?

Published online by Cambridge University Press:  20 January 2017

Steven G. Hallett
Steven G. Hallett*
Affiliation:
Department of Botany and Plant Pathology, Purdue University, 915 West State Street, West Lafayette, IN 47907
Get access Rights & Permissions [Opens in a new window]

Abstract

Invasions of many different plants have occurred in ecosystems around the world and theories of the mechanisms of these invasions abound. All the proposed theories have value, and many of the proposed mechanisms may at least serve as facilitating factors, but no overarching conceptual framework for the mechanisms of plant invasion has emerged. One common theme in all invasions is that the invading plant, in the process of geographic displacement, has been dislocated from its coevolved biota and relocated with a less-familiar biota. The impacts of dislocation from coevolved mutualists, parasites, and competitors are different but follow general principles. The impacts of relocation with new mutualists, parasites, and competitors are also variable and will change as the introduced plant coevolves with its new biotic environment. I propose some hypotheses to guide predictions of the outcomes of the dislocation of plants from coevolved relationships and, hence, the outcomes of plant geographic displacement. Invasiveness in plants is not determined by their life history traits or the nature of the ecosystem they are invading. Invasiveness is primarily a result of the process of invasion itself. When plants are dislocated from coevolved relationships and confronted with new relationships, they can become ecologically transformed. This transformation can affect the ability of a plant population to become established, invasive, and naturalized in a new environment.

Keywords

Allelopathycoevolutioninvasive speciesnatural enemiesnaturalization
Type
Weed Biology and Ecology
Information
Weed Science , Volume 54 , Issue 2 , April 2006 , pp. 282 - 290
Copyright
Copyright © Weed Science Society of America 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

Bais, H. P., Park, S. W., Weir, T. L., Callaway, R. M., and Vivanco, J. M. 2004. How plants communicate using the underground information superhighway. Trends Plant Sci 9:26–32.Google Scholar
Bever, J. D., Schultz, P. A., Pringle, A., and Morton, J. B. 2001. Arbuscular mycorrhizal fungi: more diverse than meets the eye, and the ecological tale of why. Bioscience 51:923–931.CrossRefGoogle Scholar
Blossey, B. and Nötzold, R. 1995. Evolution of increased competitive ability in invasive non-indigenous plants: a hypothesis. J. Ecol 83:887–889.CrossRefGoogle Scholar
Bond, W. J. 1994. Do mutualisms matter? Assessing the impact of pollinator and dispersal disruption on plant extinction. Philos. Trans. R. Soc. Lond. B Biol. Sci 344:83–90.Google Scholar
Bossdorf, O., Prati, D., Auge, H., and Schmid, B. 2004. Decreased competitive ability in an invasive plant. Ecol. Lett 7:346–353.Google Scholar
Buckley, Y. M., Downey, P. S., and Fowler, V. et al. 2003. Are invasives bigger? a global study of seed size variation in two invasive shrubs. Ecology 84:1434–1440.Google Scholar
Burdon, J. J., Gibson, A. H., Searle, S. D., Woods, M. J., and Brockwell, J. 1999. Variation in the effectiveness of symbiotic associations between native rhizobia and temperate Australian Acacia: within-species interactions. J. Appl. Ecol 36:398–408.Google Scholar
Callaway, R. M. and Aschehoug, E. T. 2000. Invasive plant versus their new and old neighbors: a mechanism for exotic plant invasion. Science 290:2075.Google Scholar
Callaway, R. M. and Ridenour, W. M. 2004. Novel weapons: invasive success and the evolution of increased competitive ability. Front. Ecol. Environ 2:436–443.Google Scholar
Callaway, R. M., Ridenour, W. M., Loboski, T., Weir, T., and Vivanco, J. M. 2005. Natural selection for resistance to the allelopathic effects of invasive plants. J. Ecol 93:576–583.Google Scholar
Callaway, R. M., Thelen, G. C., Barth, S., Ramsey, P. W., and Gannon, J. E. 2004a. Soil fungi alter interactions between the invader Centaurea maculosa and North American natives. Ecology 85:1062–1071.CrossRefGoogle Scholar
Callaway, R. M., Thelen, G. C., Rodriguez, A., and Holben, W. E. 2004b. Soil biota and exotic plant invasion. Nature 427:731–733.Google Scholar
Carey, E. V., Marler, M. J., and Callaway, R. M. 2004. Mycorrhizae transfer carbon from a native grass to an invasive weed: evidence from stable isotopes and physiology. Plant Ecol 172:133–141.CrossRefGoogle Scholar
Carpenter, D. and Cappuccino, N. 2005. Herbivory, time since introduction and the invasiveness of exotic plants. J. Ecol 93:315–321.Google Scholar
Castelli, J. P. and Casper, B. B. 2003. Intraspecific AM fungal variation contributes to plant-fungal feedback in a serpentine grassland. Ecology 84:323–336.CrossRefGoogle Scholar
Clay, K. 2003. Parasites lost. Nature 421:585–586.CrossRefGoogle ScholarPubMed
Connell, J. H. 1970. On the role of natural enemies in preventing competitive exclusion in some marine animals and in rain forest trees. Pages 298–312 in den Brer, P. J. and Radwell, G. C. eds. Dynamics in Populations. Wageningen, Netherlands: Center for Agricultural Publishing and Documentation.Google Scholar
Cousens, R. and Mortimer, M. 1995. Dynamics of Weed Populations. Cambridge, U.K.: Cambridge Univ. Press.CrossRefGoogle Scholar
Crawley, M. J. 1983. Herbivory and the dynamics of animal–plant interactions. Berkeley, CA: University of California Press.Google Scholar
Crawley, M. J. 1987. What makes a community invasible?. Pages 429–453 in Gray, A. J., Crawley, M. J., and Edwards, P. J. eds. Colonization, Succession, and Stability. Oxford, U.K.: Blackwell.Google Scholar
Daehler, C. C. 2001. Darwin's naturalization hypothesis revisited. Am. Nat 158:324–330.Google Scholar
D'Antonio, C. M. and Thomsen, M. 2003. Ecological resistance in theory and practice. Weed Technol 18:1572–1577.Google Scholar
D'Antonio, C. M. and Vitousek, P. M. 1992. Biological invasions by exotic grasses, the grass/fire cycle and global change. Annu. Rev. Ecol. Syst 23:63–87.Google Scholar
Darwin, C. 1859. On the origin of species by means of natural selection. London: Murray.Google Scholar
Denison, R. F., Bledsoe, C., Kahn, M., O'Gara, F., Simms, E. L., and Thomashow, L. S. 2003. Cooperation in the rhizosphere and the “free-rider” problem. Ecology 84:838–845.Google Scholar
Dobzhansky, T. 1973. Nothing in biology makes sense except in the light of evolution. Am. Biol. Teacher 25:215–129.Google Scholar
Edwards, K. R., Adams, M. S., and Květ, J. 1998. Differences between European native and American invasive populations of Lythrum salicaria . J. Veg. Sci 9:267–280.Google Scholar
Elton, C. S. 2000. The Ecology of Invasions by Animals and Plants. Chicago: University of Chicago Press.Google Scholar
Epstein, A. H. and Hill, J. H. 1999. Status of rose rosette disease as a biological control for multiflora rose. Plant Dis 80:92–101.Google Scholar
Ewald, P. W. 1987. Transmission modes and evolution of the parasitism-mutualism continuum. Ann. N. Y. Acad. Sci 503:295–306.Google Scholar
Ewald, P. W. 1995. The evolution of virulence—a unifying link between parasitology and ecology. J. Parasitol 81:659–669.Google Scholar
Fenner, M. and Lee, W. G. 2001. Lack of predispersal seed predators in introduced Asteraceae in New Zealand. N. Z. J. Ecol 25:95–99.Google Scholar
Futuyama, D. J. 2001. Ecological specialization and generalization. pp. 177–189 in Fox, C. W., Roff, D. A., and Fairbairn, D. J., eds. Evolutionary ecology: Concepts and case studies. Oxford Univ. Press, Oxford, U.K. Google Scholar
Good, R. E. 1931. A theory of plant geography. New Phytol 30:149–203.Google Scholar
Grime, J. P. 2001. Plant Strategies, Vegetation Processes, and Ecosystem Properties. 2nd ed. New York: Wiley.Google Scholar
Grotkopp, E., Rejmanek, M., and Rost, T. L. 2002. Toward a causal explanation of plant invasiveness: seedling growth and life-history strategies of 29 pine (Pinus) species. Am. Nat 159:396–419.Google Scholar
Groves, R. H. 1986. Invasion of Mediterranean ecosystems by weeds. Pages 129–145 in: Dell, B., Hopkins, A.J.M., and Lamont, B. B., eds. Resilience in Mediterranean-Type Ecosystems. Dordrecht, Netherlands: Junk.CrossRefGoogle Scholar
Halliday, J. and Somasagaran, P. 1983. Nodulation, nitrogen fixation and Rhizobium strain affinities in the genus Leucaena . Pages 27–32 in Leucaena Research in the Asia Pacific Region, Ottawa, Canada: IRDC.Google Scholar
Harley, J. L. and Smith, S. E. 1983. Mycorrhizal symbiosis. London: Academic.Google Scholar
Harper, J. L. 1965. Establishment, aggression and cohabitation. Pages 243–265 in Butler, H. G. and Stebbins, G. L. eds. The Genetics of Colonizing Species. New York: Academic.Google Scholar
Harper, J. L. 1977. Population Biology of Plants. London: Academic.Google Scholar
Hart, M. M., Reader, R. J., and Klironomos, J. N. 2001. Life-history strategies of arbuscular mycorrhizal fungi in relation to their successional dynamics. Mycologia 93:1186–1194.Google Scholar
Helgason, T., Daniell, T. J., Husband, R., Fitter, A. H., and Young, J. P. W. 1998. Ploughing up the wood-wide web? Nature 394:431.Google Scholar
Hierro, J. L., Maron, J. L., and Callaway, R. M. 2005. A biogeographic approach to plant invasions: the importance of studying exotics in their introduced and native range. J. Ecol 93:5–15.Google Scholar
Higgins, S. I. and Richardson, D. M. 1999. Predicting plant migration rates in a changing world: the role of long-distance dispersal. Am. Nat 153:464–475.Google Scholar
Hopkins, I. 1914. History of the bumblebee in New Zealand: its introduction and results. Bull. N. Z. Dept. Agric 46:1–28.Google Scholar
Inderjit, , and Duke, S. O. 2003. Ecophysiological aspects of allelopathy. Planta 271:529–539.Google Scholar
Jakobs, G., Weber, E., and Edwards, P. J. 2004. Introduced plants of the invasive Solidago gigantean (Asteraceae) are larger and grow denser than conspecifics in the native range. Divers. Distrib 10:11–19.Google Scholar
Janzen, D. H. 1970. Herbivores and the number of tree species in tropical forests. Am. Nat 104:501–508.CrossRefGoogle Scholar
Johnson, N. C., Zak, D. R., Tilman, D., and Pfleger, F. L. 1991. Dynamics of vesicular-arbuscular mycorrhizae during old field succession. Oecologia 86:349–358.Google Scholar
Julien, M. H. and Griffiths, M. W. eds. 1998. Biological Control of Weeds: A World Catalogue of Agents and their Target Weeds. Wallingford, U.K.: CABI.Google Scholar
Keane, R. M. and Crawley, M. J. 2002. Exotic plant invasions and the enemy release hypothesis. Trends Ecol. Evol 17:164–170.Google Scholar
Klironomos, J. N. 2000. Host specificity and functional diversity among arbuscular mycorrhizal fungi. Pages 845–851 in Bell, C. R., Brylink, M., and Johnson-Green, P. eds. Microbial Biosystems: New Frontiers. Proceedings of the 8th International Symposium on Microbial Ecology. Halifax, Canada: Atlantic Canada Society of Microbial Ecology.Google Scholar
Klironomos, J. N. 2002. Feedback with soil biota contributes to plant rarity and invasiveness in communities. Nature 417:67–70.Google Scholar
Kolar, C. S. and Lodge, D. M. 2001. Progress in invasion biology: predicting invaders. Trends Ecol. Evol 16:199–204.Google Scholar
Kowarik, I. 1995. Time lags in biological invasions with regard to the success and failure of alien species. Pages 15–38 in Pyšek, P., Prach, K., Rejmánek, M., and Wade, M. eds. Plant Invasions—General Aspects and Special Problems. Amsterdam: SPB Academic.Google Scholar
Kruger, F. J., Breytenbach, G. J., MacDonald, I. A. W., and Richardson, D. M. 1989. The characteristics of invaded Mediterranean-climate regions. Pages 191–213 in Drake, J. A., Mooney, H. A., di Castri, F., Groves, R. H., Kruger, F. J., Rejmánek, M., and Williamson, M. eds. Biological Invasions: A Global Perspective. New York: Wiley.Google Scholar
Levine, J. M. 2003. How effective is biotic resistance?. Ft. Lauderdale, FL: Proceedings of the 7th International conference on Ecology and Management of Alien Plant Invasions. P. 51. [Abstract].Google Scholar
Levine, J. M. and D'Antonio, C. M. 1999. Elton revisited: a review of evidence linking diversity and invasibility. Oikos 87:15–26.Google Scholar
Lively, C. 2001. Parasite–host interactions. Pages 290–302 in Fox, C. W., Roff, D. A., and Fairbairn, D. J. eds. Evolutionary Ecology: Concepts and Case Studies. Oxford, U.K.: Oxford University Press.Google Scholar
Lonsdale, W. M. 1999. Global patterns of plant invasions and the concept of invasibility. Ecology 80:1522–1536.Google Scholar
Lonsdale, W. M., Miller, I. L., and Forno, I. W. 1989. The biology of Australian weeds: Mimosa pigra L. Plant Prot. Q 4:119–131.Google Scholar
Mack, R. N. 1989. Temperate grasslands vulnerable to plant invasion: characteristics and consequences. Pages 155–179 in Drake, J. A., Mooney, H. A., DiCastri, F., Groves, R. H., Kruger, F. J., Rejmanek, M., and Williamson, M. eds. Biological Invasions: A Global Perspective. Chichester, U.K.: Wiley.Google Scholar
Mack, R. N. 1996a. Predicting the identity and fate of plant invaders: emergent and emerging approaches. Biol. Conserv 78:107–121.CrossRefGoogle Scholar
Mack, R. N. 1996b. Biotic barriers to plant naturalization. Pages 39–46 in Moran, V. C. and Hoffman, J. H. eds. Proceedings of the IX International Symposium on Biological Control of Weeds. Cape Town, Republic of South Africa: University of Cape Town Stellenbosch.Google Scholar
Mack, R. N. 2003. Plant naturalizations and invasions in the eastern United States: 1634–1860. Ann. MO Bot. Gard 90:77–90.Google Scholar
Mack, R. N., Simberloff, D., Lonsdale, W. M., Evans, H., Clout, M., and Bazzaz, F. A. 2000. Biotic invasions: causes, epidemiology, global consequences and control. Ecol. Appl 10:689–710.Google Scholar
Mallik, A. U. and Pellissier, F. 2000. Effects of Vacciniium myrtillus on spruce regeneration: testing the notion of coevolutionary significance of allelopathy. J. Chem. Ecol 26:2197–2209.Google Scholar
Marler, M. J., Zabinski, C. A., and Callaway, R. M. 1999. Mycorrhizae indirectly enhance competitive effects of an invasive forb on a native bunchgrass. Ecology 80:1180–1186.CrossRefGoogle Scholar
McKey, D. and Kaufmann, S. C. 1991. Naturalization of exotic Ficus species (Moraceae) in South Florida. Technical Report NPS/NREVER/NRTR-91/06 in Center, T. D., Doren, D. F., Hofstetter, R. L., Myers, R. L., and Whiteaker, L. D. eds. Proceeding of the Symposium on Exotic Pests and Plants. Washington, DC: National Parks Service.Google Scholar
Memmott, J., Fowler, S. V., Paynter, Q., Sheppard, A. W., and Syrett, P. 2000. The invertebrate fauna on broom, Cytisus scoparius in two native and two exotic habitats. Acta Oecologica 21:213–222.Google Scholar
Mitchell, C. E. and Power, A. G. 2003. Release of invasive plants from fungal and viral pathogens. Nature 421:625–627.Google Scholar
Molofsky, J. and Bever, J. D. 2002. A novel theory to explain species diversity in landscapes: positive frequency dependency and habitat suitability. Proc. R. Soc. Lond. B Biol. Sci 269:2389–2393.Google Scholar
Morton, J. B. and Bentivegna, S. P. 1994. Levels of diversity in endomycorrhizal fungi (Glomales, Zygomycetes) and their role in defining taxonomic an non-taxonomic groups. Plant Soil 159:47–59.Google Scholar
Mummey, D. L., Rillig, M. C., and Holben, W. E. 2004. Neighboring plant influences on arbuscular mycorrhiza fungal community composition as assessed by T-RFLP analysis. Plant Soil 271:83–90.Google Scholar
Nadel, H., Frank, J. H., and Knight, R. J. 1992. Escapees and accomplices: the naturalization of exotic Ficus and their associated faunas in Florida. Fla. Nat 75:29–38.Google Scholar
[NAS] National Academies of Science. 2002. Predicting invasions of nonindigenous plants and plant pests. Washington, D.C.: National Academies Press.Google Scholar
Packer, A. and Clay, K. 2000. Soil pathogens and spatial patterns of seedling mortality in a temperate tree. Nature 404:278–281.CrossRefGoogle Scholar
Packer, A. and Clay, K. 2002. Soil pathogens and Prunus serotina seedlings and sapling growth near conspecific trees. Ecology 84:108–119.CrossRefGoogle Scholar
Packer, A. and Clay, K. 2004. Development of negative feedback during successive growth cycles of black cherry. Proc. Royal Soc. Lond. Ser. B Biol. Sci 271:317–324.Google Scholar
Perret, X., Staehelin, C., and Broughton, W. J. 2000. Molecular basis of symbiotic promiscuity. Microbiol. Mol. Biol. Rev 64:180–201.Google Scholar
Pfennig, K. S. 2001. Evolution of pathogen virulence: the role of variation in host phenotype. Proc. R. Soc. Lond. B Biol. Sci 268:755–760.Google Scholar
Pokorny, M. L., Sheley, R. L., and Carpinelli, M. F. 2003. Designing invasive plant resistant communities by maximizing niche occupation. Ft. Lauderdale, FL: Proceedings of the 7th International conference of Ecology and Management of Alien Plant Invasions. Pp. 69–70. [Abstract].Google Scholar
Prati, D. and Bossdorf, O. 2004. Allelopathic inhibition of germination by Alliaria petiolata (Brassicaceae). Am. J. Bot 91:285–288.Google Scholar
Rabotnov, T. A. 1977. The significance of the coevolution of organisms for the formation of phytocoenoses. Bull. MOIP Biol 82:91–102. [In Russian].Google Scholar
Rabotnov, T. A. 1982. Importance of the evolutionary approach to the study of allelopathy. Sov. J. Ecol 12:127–130.Google Scholar
Radosevich, S. R., Stubbs, M. M., and Ghersa, C. M. 2003. Plant invasions—process and patterns. Weed Sci 51:254–259.Google Scholar
Read, D. J. 1988. The mycorrhizal status of Pinus . Pages 324–340 in Richardson, D. M. ed. Ecology and Biogeography of Pinus. Cambridge, U.K.: Cambridge University Press.Google Scholar
Rees, M. and Paynter, Q. 1997. Biological control of Scotch broom: modeling the determinants of abundance and the potential impact of introduced insect herbivores. J. Appl. Ecol 34:1203–1221.Google Scholar
Reinhart, K. O. and Callaway, R. M. 2004. Soil biota facilitate exotic Acer invasions in Europe and North America. Ecol. Appl 14:1737–1745.Google Scholar
Reinhart, K. O., Packer, A., Van der Putten, W. H., and Clay, K. 2003. Plant–soil biota interactions and spatial distribution of black cherry in its native and invasive ranges. Ecol. Lett 6:1046–1050.CrossRefGoogle Scholar
Rejmánek, M. 1996. A theory of seed plant invasiveness: the first sketch. Biol. Conserv 78:171–181.Google Scholar
Rejmánek, M. 2000. Invasive plants: approaches and predictions. Aust. Ecol 25:497–506.CrossRefGoogle Scholar
Rejmánek, M. and Richardson, D. M. 1996. What attributes make some plant species more invasive? Ecology 77:1655–1661.Google Scholar
Richardson, D. M., Allsop, N., D'Antonio, C. M., Milton, S. J., and Rejmánek, M. 2000. Plant invasions—the role of mutualisms. Biol. Rev 75:65–93.Google Scholar
Richardson, D. M. and Bond, W. J. 1991. Determinants of plant distribution—evidence from pine invasions. Am. Nat 137:639–668.Google Scholar
Richardson, D. M., Williams, P. A., and Hobbs, R. J. 1994. Pine invasions in the southern hemisphere: determinants of spread and invadability. J. Biogeogr 21:511–527.Google Scholar
Rouget, M., Richardson, D. M., Nel, J. L., Le Maitre, D. C., Egoh, B., and Migidi, T. 2004. Mapping the potential ranges of major plant invaders in South Africa, Lesotho, and Swaziland using climatic suitability. Divers. Distrib 10:475–484.Google Scholar
Shea, K. and Chesson, P. 2002. Community ecology theory as a framework for biological invasions. Trends Ecol. Evol 17:170–176.Google Scholar
Sheley, R. L., Krueger-Mangold, J., and Svejcar, T. J. 2003. Toward ecologically-based restoration of invasive plant dominated ecosystems: an introduction and overview. Ft. Lauderdale, FL: Proceedings of the 7th International conference on Ecology and Management of Alien Plant Invasions. P. 81. [Abstract].Google Scholar
Simberloff, D. 1995. Why do introduced species seem to devastate islands more than mainland areas? Pac. Sci 49:87–97.Google Scholar
Simberloff, D. 2003. Eradication—preventing invasion at the outset. Weed Sci 51:247–253.Google Scholar
Stohlgren, T. J., Bennett, D. T., and Kartesz, J. T. 2003. The rich get richer: patterns of plant invasions in the United States. Frontiers in Ecology and the Environment 1:1–14.Google Scholar
Strong, D. R. and Levin, D. A. 1979. Species richness of plant parasites and growth form of their hosts. Am. Nat 114:1–22.Google Scholar
Thébaud, C. A. and Simberloff, D. 2001. Are plants really larger in their introduced ranges? Am. Nat 157:231–236.Google Scholar
Thompson, J. N. 1994. The Coevolutionary Process. Chicago: University of Chicago Press.Google Scholar
Thompson, J. N. 1997. Conserving interaction biodiversity. Pages 285–293 in The Ecological Basis of Conservation: Heterogeneity, Ecosystems and Biodiversity. New York: Chapman and Hall.Google Scholar
Thompson, J. N. 1998. Rapid evolution as an ecological process. Trends Ecol. Evol 13:329–331.Google Scholar
Thompson, J. N. 1999. Specific hypotheses on the geographic mosaic of coevolution. Am. Nat 153:(Suppl.). 1–14.Google Scholar
Thrall, P. H., Burdon, J. J., and Woods, M. J. 2000. Variation in the effectiveness of symbiotic associations between native rhizobia and temperate Australian legumes: interactions within and between genera. J. Appl. Ecol 37:52–65.Google Scholar
Trappe, J. M. 1987. Phylogenetic and ecological aspects of mycotrophy in the angiosperms from an evolutionary standpoint. Pages 5–25 in Safir, G. R. ed. Ecophysiology of VA Mycorrhizal Plants. Boca Raton, FL: CRC.Google Scholar
van der Heijden, M. G. A., Klironomos, J. N., Ursic, M., Moutoglis, P., Streitwolf-Engel, R., Boller, T., Wiemken, A., and Sanders, I. R. 1998. Mycorrhizal fungal diversity determined plant biodiversity, ecosystem variability and productivity. Nature 396:69–72.Google Scholar
van der Heijden, M. G. A., Wiemken, A., and Sanders, I. R. 2003. Different arbuscular mycorrhizal fungi alter coexistence and resource distribution between co-occurring plants. New Phytol 157:569–578.Google Scholar
Vitousek, P. M., D'Antonio, C. M., Loope, L. L., Rejmanek, M., and Westbrooks, R. 1997. Introduced species: a significant component of human-caused global change. N. Z. J. Ecol 21:1–16.Google Scholar
Vivanco, J. M., Bais, H. P., Stermitz, F. R., Thelen, G. C., and Callaway, R. M. 2004. Biogeographical variation in community response to root allelochemistry: novel weapons and exotic invasion. Ecol. Lett 7:285–292.Google Scholar
Weber, E. 2003. Invasive plant species of the world: a reference guide to environmental weeds. Wallingford, U.K.: CABI.Google Scholar
Welk, E. 2004. Constraints in range predictions of invasive plant species due to non-equilibrium distribution patterns: purple loosestrife (Lythrum salicaria) in North America. Ecol. Model 179:551–567.Google Scholar
Weston, L. A. and Duke, S. O. 2003. Weed and crop allelopathy. Crit. Rev. Plant Sci 22:367–389.CrossRefGoogle Scholar
Williamson, M. H. and Fitter, A. 1996a. The characters of successful invaders. Biol. Conserv 78:163–170.Google Scholar
Williamson, M. H. and Fitter, A. 1996b. The varying success of invaders. Ecology 77:1661–1666.Google Scholar
Zedler, J. B. and Kercher, S. 2004. Causes and consequences of invasive plants in wetlands: opportunities, opportunists and outcomes. Crit. Rev. Plant Sci 23:431–452.Google Scholar