key area 3.9 - threats to biodiversity

Question 1

exploitation

Answer 1

• making the best use of natural resources eg food or raw materials

Question 2

overexploitation

Answer 2

• a resource is removed at a rate that cannot be sustained
• harvested at a rate greater than the species reproductive rate

Question 3

bottleneck effect

Answer 3

• when only a small population of a species is left, the remaining organisms may not show enough genetic variation to allow adaption to changing environments
• as a result there will be a loss of genetic diversity and inbreeding may occur which can result in poor reproduction rates and can cause severe issues for a species long term survival

Question 4

bottleneck event

Answer 4

• a mass reduction in a species population which results in the bottleneck effect eg a natural disaster

Question 5

habitat fragmentation

Answer 5

• one large habitat is broken into multiple smaller fragments perhaps due to farming or other human activities
• habitats are then prone to degradation at their edges further reducing the habitat size
• this can cause an increase in competition between species as fragment gets smaller
• species that live at the edges of fragments may colonise in the centre of smaller fragments and reduce the number of other species
• overall reduces biodiversity

Question 6

habitat corridors

Answer 6

• narrow strip of habitat joining fragments which allows species to move between fragments of the original habitat
• allows organisms to have more access to food and mates
• might allow species to recolonise after local extinctions

Question 7

introduced species

Answer 7

• non native species that has been moved by humans either intentionally or accidentally to a new geographical location

Question 8

naturalised species

Answer 8

• when an introduced species has become established within wild communities

Question 9

invasive species

Answer 9

• naturalised species that have spread rapidly and eliminated native species
• they are free free from natural predators, parasites, pathogens and competitors that limited population in original habitat, therefore allowing rapid spread
• threaten native species by preying on them, outcompeting them for resources or hybridising with them

Question 10

degradation

Answer 10

• reduction in the quality of a natural ecosystem as a result of human activity

Question 11

recolonisation

Answer 11

• returning and resettling into a habitat after a local extinction