Lectures 29 & 30: Biological Invasions Flashcards
What is a non-native species?
a species introduced to a region outside of its natural (historical) range –> has no prior evolutionary history there
What is biological invasion?
The spread and establishment of a species into a region beyond its natural range
North American smallmouth bass evolved in Mississipi river but have been introduced to BC. Are they considered native to BC?
No. Evolved in Mississippi river and then spread to BC unnaturally (cant swim across the rockies)
What is considered an invasive species?
An alien species undergoing a population outbreak that spreads rapidly causing adverse ecological effects.
How did the creation of a niagara falls canal cause invasions?
Niagara falls used to be a natural barrier (no fish could cross it) but once they build a canal, lake Ontario becomes accessible to all other great lakes, which allowed sea lamprey to invade.
What is the process of a biological invasion?
- Introduction (either natural or through human intervention)
- Establishment (becomes self sustaining)
- Geographic spread (spreads even further)
How did the great american biotic exchange occur?
N and S america became connected as sea levels dropped and the panama land bridge appeared –> mammals moved north and south, which was followed by a huge number of extinctions.
How long until a species becomes native?
A species is considered native if it evolves in that space –> if a recipient community can co-exist without damage, then the introduced species approaches nativeness.
T or F: species are now being moved long distances to regions that they could never reach without human intervention.
True!
Ex: rafting
“If humans can get there, anything can get there”
T or F: invasions are now occurring at unprecedented rates.
True!
bugs and animals end up as unwanted stowaways on cargo ships and marine life (barnacles) stick to vessels and get stuck in ballast water
T or F: invasions are not a major threat to native biodiversity.
False: invasive species with no natural predators cause disastrous effects on native populations.
They can even have a domino effect (ex; invasive snakes kill birds (which were pollinators) so now flora is less diverse)
What evidence do we have that invasions hurt native spcies?
Studies show that removing invasive species promotes native growth
Why do invasions affect islands more than mainlands?
- Less hiding spots on islands
- Less large predators –> prey aren’t used to invasive species and don’t know how to act
What is the ecological distinctiveness hypothesis?
The largest impacts are caused by species invading systems where no similar species exist.
Why are small islands sometimes less affected by rat invasions?
there are already crabs and native rats so prey know how to act around them.
