3.8 Threats to Biodiversity

Question 1

What happens as a result of over exploitation?

Answer 1

populations can be reduced to a low levels but may still recover

Question 2

Explain genetic diversity in a species

Answer 2

some species have a naturally low genetic diversity in their population and yet remain viable

Question 3

What is the bottle neck effect?

Answer 3

-small populations may lose the genetic variation necessary to enable evolutionary responses to environmental change

Question 4

What is the effect of the bottle neck effect?

Answer 4

• in small populations, this loss of genetic diversity can be critical for many species,
• as inbreeding can result in poor reproductive rates

Question 5

What has lead to habitat fragmentation?

Answer 5

the clearing of habitats

Question 6

What does the degradation of the edges of habitat fragments result in?

Answer 6

• increased competition between species as the fragment becomes smaller.
• This may result in a decrease in biodiversity

Question 7

What do more isolated fragments and smaller fragments exhibit in habitat fragmentation?

Answer 7

a lower species diversity

Question 8

What can be done to remedy widespread habitat fragmentation?

Answer 8

isolated fragments can be linked with habitat corridors

Question 9

What are the benefits of habitat corridors?

Answer 9

• allow movement of animals between fragments, increasing access to food and choice of mate
• may lead to recolonisation of small fragments after local extinctions

Question 10

What are introduced species (non-native species)?

Answer 10

species that humans have moved either intentionally or accidentally to new geographical locations

Question 11

What are naturalised species?

Answer 11

introduced species that have become established within wild communities

Question 12

What are invasive species?

Answer 12

naturalised species that spread rapidly and eliminate native species

Question 13

What is the impact of invasive species?

Answer 13

• reducing species diversity by eliminating native species
• may prey on native species,
• out compete them for resources
• hybridise with them

Question 14

What is the difference with invasive species in their current habitat from their native habitat?

Answer 14

may be free of:
-predators 
-parasites
-pathogens
-competitors that limit population
in their native habitat