- Introduced species - Lessons learned from introducing species - Dealing with invasive species
Introduced species are species that human beings have introduced from foreign ecosystems. Human beings have been introducing species for thousands of years. As commerce has increased significantly in the last five hundred years, numerous plants, animals and microbes have been transplanted from one continent to the next, sometimes intentionally and often accidentally.
Some introduced species take root in their new environments well. Some die off as they do not adjust. Others not only thrive, but destroy the local habitats and cause diseases. This is problematic and can be quite difficult to address. These introduced species are called invasive species. Invasive species are introduced plant and animal species that have destroyed native ecosystems. An example of this is the rabbit introduced into Australia that exploded and destroyed rangeland. Other invasive species include rodents, the overgrown kudzu plant in the southeastern United States, zebra mussels from Europe that have spread through the Great Lakes and the Asian long-horned beetle that has been devastating trees and forests all along the eastern United States.
There are two lessons learned from introducing species. First, the regulation of populations involves complex interactions. Second, the relationships between organisms are specific to that ecosystem. When a species is transported to a new ecosystem, it may not adapt.
Invasive species are such a big problem that there are state and federal agencies dedicated to slowing down their entry and spread.
In addition to removing and killing invasive species, a biological solution of introducing a natural enemy has also been used. This has worked effectively in the case of Spotted Knapweed, a plant from Europe accidentally introduced in the 1800s that is toxic to cattle. Scientists introduced the gall fly that eats spotted knapweed. However, the gall fly was unable to completely eradicate the knapweed because local deer mice ate gall flies. This study revealed the complex nature of ecosystems and how remedial measures need to include a comprehensive understanding of the ecosystem at hand.