3.8 Threats to Biodiversity

Question 1

Define ‘overexploitation’

Answer 1

when humans exploit the natural environment to such a level that it causes problems for ecosystems

Question 2

Describe the impact overexploitation has on population numbers

Answer 2

leads to a large reduction in populations

Question 3

Can overexploited populations recover? What factor might influence this?

Answer 3

Yes, overexploited populations may still recover.

Some species with naturally low genetic diversity can remain viable despite population decrease

Question 4

Define ‘bottleneck effect’

Answer 4

a severe reduction in the size of a population

Caused by natural disasters or human impacts

Question 5

What are two potential negative impacts of the bottleneck effect on a population?

Answer 5

1. Loss of genetic variation necessary for evolutionary responses to environmental change.
2. Increased inbreeding, which can result in poor reproductive rates.

Question 6

How does the clearing of habitats impact biodiversity?

Answer 6

It can lead to habitat fragmentation

Question 7

Define ‘habitat fragmentation’

Answer 7

Degradation of habitat edges in smaller fragments increases competition, potentially decreasing biodiversity.

Question 8

How do the size and isolation of habitat fragments affect species diversity?

Answer 8

More isolated fragments and smaller fragments tend to exhibit lower species diversity

Question 9

What are habitat corridors?

Answer 9

Habitat corridors join habitat fragments together

Question 10

How can habitat corridors help with habitat fragmentation?

Answer 10

By allowing movement of animals between fragments, increasing access to food and mates. This can lead to recolonisation after local extinctions.

Question 11

Define non-native species

Answer 11

A species that is not naturally from Scotland

Question 12

Define ‘introduced species’

Answer 12

those that humans have moved either intentionally or accidentally to new geographic locations

Question 13

Define ‘naturalised species’

Answer 13

those that become established within wild communities

Question 14

Define ‘invasive species’

Answer 14

naturalised species that spread rapidly and eliminate native species

Question 15

Explain how invasive species impact species diversity

Answer 15

Reduce species diversity by killing native species

Question 16

Why do non-native species often become invasive in new environments?

Answer 16

Because they are often free from:

• Predators
• Parasites
• Pathogens
• Competition

All of these would limit their growth in their native habitat

Question 17

What are three ways invasive species can negatively impact native species?

Answer 17

• They may prey on native species.
• They may outcompete native species for resources.
• They may hybridise with native species.

Domestic cats and wildcats are an example of hybridisation