Lecture 15 Extinction

Question 1

The 6th mass extinction (7)

Answer 1

*Currently happening
*Mainly due to human activity
*Agriculture
*Deforestation
*Commercial fishing
*Greenhouse gases
*climate change

Question 2

Biodiversity objective

Answer 2

To maintain sustainability for a long time and prevent plant and animal species from being extinct

Question 3

Biodiversity Crisis (4)

Answer 3

1, Destruction of natural habitats
2. Excessive commercial harvesting or overexploitation
3. Stressors associated with the human economy
4. Invasive species

Question 4

Destruction of natural habitats (definition and 2 things about deforestation)

Answer 4

*Conversion of natural ecosystems into agro-ecosystems

• Deforestation
  – Particularly problematic in old growth forests as Old growth trees are carbon stores
  – Tropical forests have a high species richness

Question 5

Excessive commercial harvesting or overexploitation (Oceans) (3)

Answer 5

• Feed us and many other species
• Regulate our climate (currents)
• Provide the majority of Earth’s oxygen (phytoplankton)

Question 6

Excessive commercial harvesting or overexploitation (Islands) (4)

Answer 6

*Majority of extinctions have occurred on islands
*Species evolved with the absence of predators
*island pops are typically small which increases risk for extinction
*Humans introduced competitors, diseases, or hunted the animal Ex: Dodo Bird

Question 7

Stressors associated with the human economy (4)

Answer 7

Dams
*Alter river flow
* Alter habitats (Change from free-flowing river to reservoir)
* Block rivers (Block migratory routes, Isolate populations)
* Hold back sediments/nutrients from areas downstream