Main terms used to talk about biological invasions
Invasive alien species (IAS): in accordance with the IUCN definition, the Convention on biological diversity, the European parliament and the Council of Europe, an invasive alien species is a species introduced by humans outside their natural range (intentionally or accidentally) and whose establishment and spread threaten native ecosystems, habitats or species with ecological and/or economic and/or negative health.
Not all introduced species induced negative consequences on the ecosystem they occur. Only a part of them is at the origin of negative impacts, direct or indirect, at different levels. They can cause serious ecological impact by affecting the specific composition and the functioning of host ecosystems, generate socio-economic consequences by disrupting economic activities (agriculture, forestry, etc.) and affect humain health.
IAS are encountered in every taxonomic groups : virus, fungi, algae, vascular plants, invertebrates, reptiles, amphibians, birds, fishes, mammals, etc.
It would be more appropriate to talk about alien invasive populations rather than species, the term “species” gathering all the populations, those from the natural range as those from the introduced area (Pascal et al., 2006). That’s why the definition could include the term “population” instead of “species”. Moreover, all introduced population of the same species are not likely to become invasive.
Biological invasion: phenomenon of expansion of a species out of her natural range, forming perennial and autonomous populations without human assistance, generally in three phases: arrival, establishment and expansion.
Introduction: deliberate or accidental displacement by humans of an alien species outside of its natural range, past or present. This movement can take place between different countries or within the same country.
Intentional introduction: deliberate displacement and/or liberation by human of an alien species outside o its natural range.
Accidental introduction: any introduction that is not deliberate.
Alien species (or introduced species): a species, subspecies or lower taxon introduced by human outside of its natural range or any part, gamete, seed, egg or propagule of that species capable of surviving and reproducing thereafter.
Naturalized species: an exotic species, subspecies or lower taxon whose populations reproduce and are self-perpetuating without human assistance.
Native species: a species, subspecies or lower taxon naturally occurring within a territory, including the area it can reach and occupy using its own means of movement.
Endemic species: a species, subspecies or lower taxon whose geographic distribution is limited to a territory (an island, a mountain, a valley, etc.) and is not found elsewhere in the natural state.