From Envirowiki

Invasive species frequently demonstrate three specific characteristics: adaptability, aggressive reproduction, and vigorous growth. Invasive species thrive in numerous conditions by adapting to the environment. They can live in a wide variety of environments subject to aridity/humidity, direct/indirect radiation, and varying edaphic conditions. These species are able to adapt to changing conditions in terms of intra- and inter- annual variability in rainfall and radiation. Sometimes invasions are able to occur when potential competitors are not growing, which makes it easier for the invasive species to thrive since they are not competing for nutrients, sunlight, water, etc. If the biotic invader reproduces more aggressively than competitors than it is easier for an invasion to occur. Also, the rate of growth increases the success of an invasion by out-competing slow growing plants. These three features have enabled scientists to create a predictive profile of likely invaders. This profile can be applied to the management and control of invasive species.

[edit] 1 How to create an invasive species

Species are generally only invasive if they somehow breach a barrier that previously kept them in check: over a long timespan, any ecosystem will evolve checks and balances; either predators to eat any overly-abundant species, natural defenses for the abundant species predators, or simply a lack of food, due to over-predation. Once this evolution is reached, the species will become a part of the ecosystem. This process can take millions of years.

Barriers that keep species in check include: predators, temperature ranges, geographical boundaries (mountain ranges, oceans, differing ecosystems, such as forests between two deserts), water, etc. Humans are adept at creating invasive species, by bringing them with them on colonial outings (intoduced species). Massive problems have been caused this way in Australia with rabbits, foxes, cats, lantana, privet, the cane toad, and numerous other species. Similarly, colonial-minded gents (usually male, anyway), who decided that Australian wattle and eucalypts looked nice exported them to south america, and south africa, where they are now incredibly invasive due to lack of predators.

Another method that humans are getting close to achieving is through genetic modification. GM can be used to create strains of organisms that are predator-resistant, meaning they have the potential of becoming a superweed, which is pretty much the same thing as an invasive species, but more super.

[edit] 2 Sources

“Comparing Invasive Networks: Cultural and Political Biographies of Invasive Species” by Paul Robbins