lec 29-30: Biological invasions Flashcards
what is a non-native species?
A species introduced outside of its natural (historical) range (i.e where it evolved)
no evolutionary history to the region
what is a Biological Invasion
The spread and establishment (i.e forms a self-sustaining population) of a species into a region beyond its natural range
leaving it’s historic range boundary and entering an invaded range
what is the process of biological invasion
(its a circle)
Introduction
(formation of self-sustaining population)
Establishment
(impacts often detected here)
Geographic spread
(natural or human-assisted dispersal)
Back to introduction
What is an “invasive” species?
An introduced (alien) species that spreads rapidly (i.e a highly successful invader)
What is the Great American Biotic Exchange
(around 3 million years ago) when North and south America connected by the Panama land bridge
- mammals moved north and south
A series of extinctions followed on both continents
T or F: Species are being moved long distances to regions that they could never reach without human assistance
True
What are Wallace’s Biogeographic Realms
There are 7:
narcotic
neotropical
Ethiopian
Palaearctic
oriental
Australasian
explains the distribution of animals and plants as a result of geographical changes
(not a question) New Zealand
NZ is a good example of man-made importations of non-native species. NZ is now home to goats, cats, foxes, deer
Is the antarctic spared from biological invasions
No! because humans go there and always carry with them organisms (like seeds under their shoes) So the Antarctic is also at risk from invasion
T or F: Invasions are now occurring at unprecedented rates
TRUE
How does the global (ship) transportation system contribute to biological invasions? (3 examples)
- Unwanted stowaways
- Organisms on ship hulls
- Ballast water
T or F: more or less 7000 species are carried in ships at any given time
TRUE
What are the differences between natural (prehistoric) and human-assisted invasions?
- The frequency of long-distance dispersal events is now very high
- The number of species transported per event is now potentially large
- The variation in mechanisms and routes of dispersal are now extremely large
- Invasions between biogeographic realms are now common
- the potential for synergies with other stressors are now very high
T or F: Invasive species are a major threat to native biodiversity
TRUE
what is the average contribution of invasions in animal extinctions
Gobal animal = 62%
Fish = 48%
mammal = 69%
bird= 60%
reptile= 57%
T or F: Non-native consumers cause more damage to prey populations than do native consumers
TRUE
what is the ecological distinctiveness hypothesis
the largest impacts are caused by species invading systems where no similar species exist
T or F: Invasions can disrupt ecosystems, often in unpredictable ways
TRUE
What is the synergistic relation between invasive mussels, warm temperature, botulism and waterfowl
The invasive zebra mussels -> Filtration activity -> improves water clarity -> Excessive growth of algea and plants-> Algal die-offs reduce the oxygen (also caused by warmer temperatures) -> promotes botulism bacteria -> consumed by zebra mussels -> consumed by round goby fish -> consumed by waterfowl -> waterfowl dies
T or F: Invasions degrade ecosystem services and cause a broad range of socio-economic impacts
TRUE (i.e crop pests invasions)
What should be done to reduce invasions? (4)
- Create systems of early detection and rapid response at national and international scales
- Develop better risk assessment methods for identifying and prioritizing high-risk invaders
- identify and control emerging vectors and pathways
- tighten regulations concerning trade in live organisms
