Selection Pressures and Extinction

Question 1

What is extinction?

Answer 1

The process of death of all members of a population or species. May result in genes being permanently lost from the gene pool.

Question 2

Why are sufficient levels of biodiversity good?

Answer 2

Genetic diversity allows a population to evolve and adapt through natural selection effectively. With low genetic diversity, a species could be easily wiped out.

Question 3

What can low biodiversity result in?

Answer 3

Low ecosystem stability.
- Inertia: Ability to resist disturbance
- Resilience: Ability to recover from external disturbance

Question 4

What is a selection pressure?

Answer 4

Is any feature of an environment that increases or reduces the fitness of a particular phenotype in a population of organisms.

Question 5

What are 6 examples of selection pressures?

Answer 5

1. competition for food
2. mates
3. space
4. predators
5. climate
6. food sources

Question 6

What can change selection pressures result in?

Answer 6

Drive evolution but may also lead to extinction if populations don’t have time to evolve.

Question 7

What are examples of habitat destruction?

Answer 7

Land clearing for agriculture, mining or housing. Fire regimes changed due to European settlers.

Question 8

What are examples of climate change?

Answer 8

Global warming affects weather patterns. Includes temperature, sea level, rainfall, wind and ocean currents.

Question 9

Why should plants be particularly affected by climate change?

Answer 9

As they cannot move away from adverse conditions. This effect flows onto animals.

Question 10

What are examples of introduced species?

Answer 10

Predators such as foxes, cane toads and cats. Competition such as rabbits and prickly pear and diseases like chytrid fungus.

Question 11

What are examples of pollution?

Answer 11

Air pollution from particulates and photochemical smog from fossils. Land pollution by dumping wastes and chemicals. Water pollution from fertilisers, crude oil and chemical residues.

Question 12

Why are populations with reduced genetic diversity at risk of extinction?

Answer 12

• Population cannot evolve to changing environments because there are fewer genetic differences between individuals.
• Diseases can spread quickly through the population as they are more suitable to environmental changes.