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18 Cards in this Set
- Front
- Back
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What is an alien species? |
A species occurring outside of its natural range and dispersal potential |
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What is an alien invasive species? |
An alien species which becomes established in natural or semi-natural ecosystems or habitat, is an agent of change, and threatens native biological diversity |
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Give some example of alien species |
- Muntjac deer - Australian swamp stonecrop - Rhododendron - Japanese knotweed |
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What are some of the impacts of the introduction of Starling in the US |
- agricultural damage to crops - compete with native fauna for food - usurping nests - can damage infrastructures |
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What is the main reason for the accidental introduction of Mnemiopsis leidy? |
Ballast tanks |
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What are some of the characteristics of the tropical water invader, the water hyacinth |
- occupies the water surface: few competitors - buoyant, mobile - fragments regenerate into plants - flowers are self-fertile |
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What are the four stages of an invasion? |
1. introduction 2. escape and establishment 3. spread 4. infestation |
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What is the 'tens rule'? |
~ 10% of introductions become established ~ 10% of established aliens become invasive |
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What are the economic effects of invasive species? |
- exotic species in the US cost $100 billion in 1993 - direct damage to crops, houses and waterways - control costs |
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What are the ecological effects of invasive species? |
- swamping - spread disease - hybridization - extinction by predation |
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How many species are aliens in the British Isles? |
1,264 |
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Name a few alien species in the British Isles |
- Sitka deer - Mallard duck |
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What is biological control? |
Aims to eliminate harmful alien species by introducing its natural predator or pathogen |
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What are the key factors to consider prior to introduction of a biological control? |
- the controlling species must be specific to its target - the control species must be screened to remove its own predators and parasites - populations of the controlling species must be largely determined by its food supply, the alien pest |
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What are some examples of successful biological control? |
- Prickly pear by moth caterpillars - Kariba weed by beetles |
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What is formed when a GM crop cross-fertilises with a wild or weedy plant? |
GM hybrid |
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How many hybrids are estimated each year? |
32,000 |
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