3.8 Threats to Biodiversity

Question 1

Overexploitation

Answer 1

Reduces numbers in population, reduces genetic diversity of that population

Question 2

Bottleneck effect

Answer 2

Small populations may lose genetic variation necessary to enable evolutionary responses to environmental change

Loss of genetic diversity can be critical for many species as inbreeding results in poor reproductive rates

Question 3

Habitat fragmentation

Answer 3

Separation of an organism’s preferred habitat, caused by geological processes or by human activity

Degradation of edges of habitat fragment increase competition between species (smaller fragment)

To remedy widespread habitat fragmentation, isolated fragments can be linked with habitat corridors

Question 4

Habitat corridors

Answer 4

Corridors are pathways of natural habitat, allow movement of animals between fragments, increases access to food and choice of mate

May lead to recolonisation of small fragments after local extinctions

Question 5

Introduced (non-native) species

Answer 5

Species that humans moved intentionally or accidentally to new geographical locations

Question 6

Naturalised species

Answer 6

Species that become stablished within wild communities are termed naturalised species

Question 7

Invasive species

Answer 7

Are naturalised species that spread rapidly and eliminate native species, reducing species diversity

May be a lack of natural predators, parasites, pathogens and competitors that would normally limit their population

They may prey on native species, outcompete them for resources or hybridise with them