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Population Dynamics (The likeliness of biological invasions is determined…
Population Dynamics
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Patch Occupation Models assess how different colonisation probabilities can influence invasion processes
Divided into three different levels; High, Medium & Low.
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If Colonisation is equal or smaller than Extinction = Then the species is thought to have naturalised
If Extinction is greater than Colonisation = established
If colonisation is much greater than extinction = invasive
There are four main ways to promote invasiveness:
1. Propagule Pressure
2. Intrinsic Rate
3. Biotic/environmental conditions
4. Population Size
Three main categories for level-based traits that promote invasiveness in non-native species:
Event-Level Traits
Location-Level Traits
Species-Level Traits
Event-Level Traits
This trait is concerned with the size and number of introductions and individual non-native species present at one particular time as this will contribute to the probability of success or failure regarding establishment.
Location-Level Traits
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This hypothesis proposes that the reason non-native species thrive in new environments and end up becoming invasive is due to the lack of natural enemies in the new environments.
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Habitat Selection
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The best invaders are often species that have evolved in agricultural landscapes - as these landscapes are disturbed frequently.
Species-Level Traits
This includes taxonomic isolation!
This basically means that non-native species that are very different from the type of species found in the invaded environment have a better chance of becoming established compared to non-native species that are similar to the invaded environments species.
This is linked with the natural enemy release hypothesis - whereby non-native species that are introduced that are very different to species found in the invaded environment are less likely to find natural enemies in this landscape and therefore will thrive free from predation