7.4,5,12 Contd: Modes Of Natural Selection

Question 1

What is reproductive success measured by?

Answer 1

Relative fitness

Question 2

What is relative fitness?

Answer 2

• The number of surviving offspring that an individual produces compared to the
  number left by others in the population.

Question 3

How can effects of natural selection be measured by?

Answer 3

Examining the changes in the mean of phenotypes

Question 4

What are the three modes of natural selection?

Answer 4

1. Directional selection
2. Stabilizing selection
3. Disruptive selection

Question 5

What is directional selection

Answer 5

Selection towards one extreme phenotype

Question 6

What is stabilizing selection?

Answer 6

• Selection towards the mean and against the extreme phenotypes

Question 7

What is disruptive selection? (2)

Answer 7

• Selection against the mean

- Both phenotypic extremes have the highest relative fitness

Question 8

What is sexual selection?

Answer 8

• A type of natural selection that explains why many species have unique /showy traits

Question 9

What type of structures do males usually have in sexual selection? (2)

Answer 9

• useless structures (like colorful male peacock feathers) simply because females choose that trait
• can produce traits that are harmful to survival (colorful feathers make them easier to spot in predators)