Community invasibility

Question 1

Europe-North America asymmetry explanations

Answer 1

1 - Differential opportunity
2 - Size of donor pools
3 - Ecological opportunity
4 - Intrinsic superiority of donor pool

Question 2

6 things that make some communities more invasible than others

Answer 2

1. Fluctuating resource availability
2. Disturbance
3. Vacant niches
4. Enemy release
5. Biotic Resistance
6. Biotic Facilitation and Invasional meltdown

Question 3

Resource availability equation

Answer 3

Supply - Uptake

Question 4

Fluctuating Resource Availability hypothesis

Answer 4

Factors that increase the availability of resources will increase the vulnerability of a community to invasion.

Question 5

4 predictions of the Fluctuating resource availability hypothesis

Answer 5

1. Areas subject to pronounced fluctuations in resource supply are more susceptible to invasion
2. Community invasibility will fluctuate over time
3. Invasibility will increase following disturbance
4. Invasibility will increase following introduction of herbivores into nutrient rich areas

Question 6

what does land disturbance mean for invasion risk

Answer 6

• Frees up resources by disrupting resident species
• Invasions more noticed on disturbed land by humans
• more opportunities for human vector dispersal

Question 7

Niche definition

Answer 7

Total set of physical and biological requirements of a species, and its ecological role in the environment

Question 8

Vacant niche hypothesis

Answer 8

Invasions are more likely to occur in habitats with “vacant niches”

Question 9

Competitive Exclusion principle

Answer 9

No competing species can occupy the same niche in a stable environment

Question 10

Darwins Naturalization hypothesis

Answer 10

Introduced species belonging to novel genera are more likely to establish - because they avoid competitive exclusion

Question 11

Enemy release hypothesis

Answer 11

Species are suppressed in their native range by natural enemies. Escape from these enemies enables introduced populations to grow explosively

Question 12

Evolution of increased competitive ability

Answer 12

When released from specialist herbivores, introduced plants can allocate more resources toward growth rather than defence

Question 13

“Enemy of my enemy is my friend” example

Answer 13

Two parties can benefit each other if they share one enemy.

Red Squirrels and Grey Squirrels in the UK. Grey squirrels were introduced to the UK where they competed with the native red squirrel. The Grey squirrels brought a virus that is bad for reds, therefore the pox takes out the red squirrel population.