Threats to Biodiversity

Question 1

Describe exploitation and the effect it has on genetic diversity

Answer 1

• Overexploitation population size may be reduced but can still recover.
• Some species have low genetic diversity but can remain viable.
• For some small populations, loss of genetic diversity can be critical as imbreeding can lead to low reproductive rates.

Question 2

What is the bottleneck effect

Answer 2

Small populations lose the genetic variation needed to enable evolutionary responses to environmental change.

Question 3

What is habitat loss and habitat fragmentation

Answer 3

Clearing of habitats led to habitat fragmentation. Degradation of the edges of habitat fragments leads to increased competition between species. This may result in a decrease in biodiversity. More isolated and smaller fragments have lower species diversity.

Question 4

How can habitat fragments be remedied

Answer 4

Habitat corridors which allow movement between fragements increasing access to food and choice of mates. This may lead to recolonisation after local extinction.

Question 5

What is a introduced, naturalised and invasive species?

Answer 5

Introduced: A non-native species that humans have mored (intentionally or accidentally) to a new geographic location.

Naturalised: Non-native species that become established within wild communities.

Invasive: Naturalised species that spread rapidly and eliminate native species therefore reducing species diversity. They may be free of any predator, competitior or pathogen that would limit their population in their natural habitat. They may prey on, out-compete or hybridise with native species.