overharvesting as global change

Question 1

what is a genetic bottleneck?

Answer 1

when there is loss of a population and the recovery of individuals does not restore the loss of genetic diversity

Question 2

what is the Quartenary Extinction Event?

Answer 2

global trend in selective extinctions in mammals over 44kg
- further from Africa, there was greater percentage of extinctions
- ancestors of homo sapiens responsible (overkill hypothesis)

Question 3

what were the ecological impacts of the Quartenary Extinction Event?

Answer 3

• loss of the large mammals that are mostly herbivores meant that many plant species became dominant
• increase fire frequency because less grass grazers led to growth of grasses which is perfect fuel for wildfires

Question 4

what are some patterns in modern overharvesting?

Answer 4

• selective exploitation of apex predators
• removal of largest animal from a community
• targetting species that are viewed as most valuable
• eradication of species that are viewed as undesirable
• wildlife viewed as a resource

Question 5

what is the Krill Paradox?

Answer 5

loss of main krill predator (whales) should have led to increase in krill numbers but instead they declined with the whale population
-> krill depend on nutrient input from whale poops

Question 6

what are some examples of wildlife adapting to overharvesting?

Answer 6

• cod maturing earlier and making less eggs
• increase incidence of tuskless elephants in heavily hunted populations