Drivers of biodiversity decline

Question 1

What are the 4 drivers of biodiversity decline?

Answer 1

1. Overexploitation
2. Habitat loss and fragmentation
3. Introduced species
4. Chain of extinction

Question 2

Give an example of overexploitation

Which species are most vulnerable and why?

Answer 2

Hunting - large species are most vulnerable, they have slow reproductive rates, they move more slowly and provide more food
Decline in large species fits with the timing of human colonisation

Question 3

Define habitat loss and fragmentation

Answer 3

Loss of habitat area and therefore a loss of species

Question 4

Why is one large reserve better than many small ones?

Answer 4

The edge effect - one large reserve removes the amount of edge meeting matrix (e.g. agricultural land)
Corridors between reserve patches allow movement

Question 5

Why do introduced species cause a decrease in population?

Answer 5

• Species that evolve in isolation may not have resistance to disease or predation
• Some traits predispose some species to be better competitiors than the native species
• Ecosystem level effects

Question 6

What is the chain of extinction?

Give an example

Answer 6

Serial effects e.g. Sea lion population crashes, killer whales start eating sea otters, kelp forests disappear