11.4 - Directional & Stabilising Selection

Question 1

Two types of selection

Answer 1

• directional
• stabilising

Question 2

What is stabilising selection?

Answer 2

• natural selection that keeps allele frequencies relatively constant over generations
• stays constant unless there’s a change within the environment

Question 3

What is directional selection? Why does it occur and for what reason?

Answer 3

• natural selection that produces a gradual change in allele frequencies over several generations
• happens when there’s a change in environment/selection pressures or a new allele has appeared which is advantageous