Alien Species

Question 1

Native species

Answer 1

Indigenous taxa found within their natural distributional range

Question 2

Alien species

Answer 2

(Non-native, non-indigenous, foreign, exotic) Taxa found outside their natural distribution range and their occurrence is directly resultant from and possibly sustained by human intervention

Question 3

Invasive species

Answer 3

Taxa found outside their natural distribution range as a result of human intervention and which have become established in natural or semi-natural habitats; they act as agents of habitat change and threaten native biodiversity

Question 4

Adventive species

Answer 4

Taxa that naturally colonise new areas and are usually associated with early stages of succession

Question 5

Introduction

Answer 5

The deliberate or accidental movement by humans of taxon outside its natural range

Question 6

Naturalised species

Answer 6

Alien species that reproduce consistently and sustain populations over more than one life cycle without direct intervention by humans

Question 7

Neophyte

Answer 7

Species introduced within <500 years

Question 8

Archeophyte

Answer 8

Species introduced over 500 years

Question 9

How can species be introduced?

Answer 9

Deliberate; Moving eggs, seeds, spores, vegetative parts or whole organisms, introduction clubs
Non-deliberate: Turned up fields, muddy shoes etc
Can also be introduced for economic gain e.g. wheat cattle

Question 10

Pacific Aliens (Hawaii)

Answer 10

Have 900 native species and 4000 introduced plants, only 91 are invasive and will take over if not maintained, the 3rd biggest threat to biodiversity, due to lack of natural checks

Question 11

New Zealand

Answer 11

Flora doubled as a result of ‘introduction clubs’, wanted to make settled land more like home. Also introduced 30 million foxes to act as pest control, but became pests.

Question 12

Unintentional effects of AS

Answer 12

Faucet snail: Population sizes too big and fouled surfaces
Chinook Salmon: Ecological and genetic effects on native species
Western Mosquitofish: Displacement of native species
Can also kill humans e.g. bubonic plague, smallpox

Question 13

The economic cost of aliens

Answer 13

Cost UK $12 billion every year.
In South Africa, the Nile perch is one of the largest freshwater fish and has led to the extinction of 200 endemic fish species through predation or competition for food.

Question 14

Threats created by AS

Answer 14

Replacement of diverse ecosystems with single species
Invasion leading to extinction
Direct threat to natural fauna
Alternation of soil chemistry

Question 15

How do Aliens invade?

Answer 15

Introduction: Either accidental or deliberate
Naturalisation: Establish initial populations and expand
Facilitation: Parallel introduction or fostering by humans
Spread: Efficient growth rates, fecundity and high dispersal
Biotic interactions: Fit in or push out
Stabilisation: Boom and bust

Question 16

Characteristics of invasive animal species

Answer 16

Adaptability
Fast growing and maturity
High fecundity 
Broad diet
High migration ability
Aggressive competitor

Question 17

Characteristics of invasive plant species

Answer 17

Short and long dispersal 
Self-pollinating 
Seed longevity 
Can germinate in favourable conditions 
Early seed maturation 
Copious seeding

Question 18

Characteristics of Host Habitats

Answer 18

Absence of specific predators 
Balance of nature 
Empty niche
Chemical change 
Disturbance

Question 19

How to prevent AS

Answer 19

Prevention is better than cure
Need to be maintained
Use the legislation

Question 20

How to control and manage the introduction of AS

Answer 20

1. Assessment
2. Experimental
3. Introduction
4. Data monitoring
5. Liability

Question 21

Why are remote islands so vulnerable?

Answer 21

Species poverty (few species)
Evolved in isolation 
Small scale 
Crossroads if intercontinental trade
Lack of previous pests or diseases