1. Climate change

Changing climate patterns contribute to invasion.

2. Community species richness

The process of invasion is affected by community species richness.

3. Disturbance

Alteration of the habitat due to natural phenomena (fire, mudslides, flooding etc.) or due to human disturbances contributes to invasion.

4. Ecosystem engineers

The invasive species alters the environment in a way alters ecosystem function, niche structure or the competitive landscape.

5. Empty niche

The invasive species uses resources that are unexploited in the invaded range.

6. Enemy of my enemy

A third species interacts with a negative effect on native species in the introduced range, contributing to the success of an invasive species.

7. Enemy release

The invasive range of a species may not include the natural enemies or similar organisms that limited its populations in the native habitat.

8. Evolution in general

The invasive species evolves to become different from the native ancestor (due to various responses to selection or other evolutionary changes, but distinct from EICA and other specific evolutionary hypotheses listed here).

9. Evolution of increased competitive ability (EICA)

Due to the relaxation of predation or herbivory, the invading species may evolve traits that permit it to become a better competitor in the invasive range than in the native range.

10. Fluctuating resources

Ability to exploit repeated changes in resource levels permits an introduced species to become an invader.

11. Hybridization

The invasive species may be the product of intraspecific hybridization between populations from different parts of the native range, or interspecific hybridization with other species native to the invaded or any other area.

12. Inherent superiority

The invasive species possesses traits that make it superior (due to particular traits may be specified).

13. Mutualism, facilitation or invasional meltdown

Another organism in the novel environment facilitates the success of the invasion.

14. Novel weapons

The invasive species has characteristics that negatively affect the species it interacts with in the introduced range in the specific ways identified explicitly by this hypothesis.

15. Plasticity

An invasive species has a highly plastic phenotype that is capable of enhanced response to environmental conditions (often resource levels) found in an introduced range, that contributes to its establishment or competitive success.

16. Preadaptation to climate

The existing environmental tolerances of an introduced species allow it to become invasive in the matching environmental conditions in a new range.

17. Propagule pressure

Invasion is the result of a large number of propagules being introduced to the invaded environment.

18. Other

Any other hypothesis on invasions not defined above.