Invasion Ecology: Understanding the Impact of Introduced Species, Study notes of Ecology and Environment

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LECTURE 15 INVASION ECOLOGY

Pg. 19; 490-1; 504-

1. What’s the difference between an introduced Non-native or exotic species moved accidentally or deliberately to new ecosystem vs. invasive introduced species that spread after establishment species?
2. What are examples of introduced species in Illinois? Emerald ash borer, long-horn beetle, purple loosestrife, zebra mussel, garlic mustard…..
3. What are the three stages required for an introduced species to become invasive? A. arrival B. establishment C. spread ARRIVAL
4. What are general mechanisms by which species are deliberately introduced? immigrants bringing from native country; Shakespeare fans; game animals; domestic animal What is one specific example of a specific species that was introduced deliberately? starling Why was it introduced? occurs in Shakespeare; fan wanted all here.
5. What are general mechanisms by which species are accidentally introduced? ship ballasts; unprocessed wood; fruit shipments; by-pass natural barriers What is one specific example of how your own actions might cause an introduction? on shoes or in luggage when return from foreign country; throw out of our cars ESTABLISHMENT
6. What are traits of introduced species that make them more likely to be successfully established?

_1. non-specific diet and habitat needs 2. self-fertilization

3. small body size 4. high reproductive potential (r-strategy)
4. good competitor 6. social/ gregarious_ SPREAD

7. What are three hypotheses that explain why an introduced species successfully spreads? A. escape from natural enemies B. increased competitive ability C. pre-adapted to disturbed habitats
8. What are three general mechanisms by which introduced species displace (eliminate) native species? A. Can act as predator, competitor, parasite, pathogen B. Can modify habitat C. Can promote spread of other invaders
9. Relative to other causes, how important are invasive species as threats to endangered species? They rank #2 – behind habitat degradation and loss; ahead of pollution, overexploitation, disease.

10. Explain this argument: It does not matters whether a species is displaced because the lost species is replaced by the new species in a community. The number of species stays the same. One species plays the same as another in the community so the identity does not matter. An introduced species will play no havoc. Do you agree with the argument that replacement of a native species by an introduced species is no problem? Why or why not? No. The introduced species may have similar traits, but it may not have its native enemies to control it. It may be more competitive than the native species and replace more than 1 species.
11. Human activities are resulting in “biotic homogenization”. Explain this statement. As we destroy and modify habitats, we have fewer diverse habitats. Also as we introduce species that become widespread and display local native species, widespread areas become more similar in terms of types of habitats and species within them. Diverstiy is lost.
12. What are four hypotheses that relate to the types of ecosystems that are particularly vulnerable to invasion by introduced species? A. Biotic resistance to invasion via high species diversity. B. Disturbance with fewer species and more open niches allows invasion. C. Human areas have many species that have been associated with humans for a long time. D. Species on islands have little evolutionary history with competitors and natural enemies.
13. Summarize what are the major ecological (not economic) costs of invasive species. They displace native species; alter native species’ interactions; modify habitat; change ecosystem processes
14. What are three ways in which we attempt to control invasive species? A. use of pesticides and herbicides B. biological control via introduction of a natural enemy from native range. C. minimize disturbance to landscape What are problems associated with use of pesticides/herbicides? Can kill more species than the targeted invasive species. Can be a selective agent for resistance to the pesticide. Can pose health risks to humans What are potential problems with use of biological control? If it is not species-specific affecting only the invasive species, it can affect other species.
15. How can we prevent problems arising from introduced/invasive species? Education, research for generalities; monitor for early detection; use quarantine once found so doesn’t spread; increase regulations