An invasive non-native species is one that has been transported outside of its natural range and that threatens environmental, agricultural or economic resources. Non-natives are one of the primary threats to global biodiversity, second only to habitat destruction.
In the past, natural barriers such as oceans, mountain ranges and inhospitable climates have allowed unique ecosystems and species to evolve. Increasing levels of activities such as global trade, tourism and travel have resulted in an unprecedented dispersal of species into new habitats throughout the world.
In their new habitat these species are without their natural competitors or predators and they are able to dominate or out-compete other species. Once established, invasive species are often very difficult and costly to control or eradicate, which is why prevention is so important.
The problems caused by invasive non-native species are likely to increase in line with further globalisation, increased travel, and the effects of climate change.