About Invasive Species

What are they?

The International Union for Conservation of Nature, (IUCN) describes invasive species as “animals, plants or other organisms introduced by man into places out of their natural range of distribution, where they become established and disperse, generating a negative impact on the local ecosystem and species.” Invasive species can negatively impact human health, the economy (i.e. tourism, agriculture), and native ecosystems. These impacts may disrupt the ecosystem processes, introduce diseases to humans or flora and fauna, and reduce biodiversity.

Invasive species are organisms that have been transported from their native environment to a new environment. Depending upon the transportation distance, these species may be removed from competitive factors (i.e. pathogens, pests, predators) that limit their abilities to disrupt native and human altered ecosystems.

Research has demonstrated that invasive species have characteristics that allow them to outcompete native species and change biodiversity, community structure, and ecosystem processes in a region. These traits include: rapid growth, short life cycle (reproduce seeds within a few years), prolific seed production, seed dormancy with staggered germination, toleration of a wide range of environmental conditions, generalist pollinators, varied reproductive strategies and efficient dispersal abilities. Early successional species tend to be good colonizers, but the complex species interactions and characteristics that allow a species to disrupt ecosystems are elusive.

Research indicates that the introduction of species and their interactions with the native biota and non-native biota are changing the way ecosystems function. Novel ecosystems are forming from these introductions. The increasing introduction and spread of invasive species, global climate change and habitat alteration are the most serious threats to global biodiversity. These factors can produce a synergistic effect, where there is a rapid acceleration of the loss of biodiversity in a region. Conservation efforts are not able to keep pace with the impacts of invasive species.

Related links:

The list of '100 of the World's Worst Invasive Alien Species' illustrates the incredible variety of species that have the ability, not just to travel in ingenious ways, but also to establish, thrive and dominate in new places. Today, alien invasion is second only to habitat loss as a cause of species endangerment and extinction.

Click here to view images and follow links to species profiles of '100 of the World's Worst Invasive Alien Species' on the Global Invasive Species Database.