18.5 - Types of Selection

Question 1

What are selection pressures?

Answer 1

Environmental factors affecting survival and reproduction

Question 2

What are examples of selection pressures?

Answer 2

• Predation
• Competition
• Disease

Question 3

Why is over-production of offspring important?

Answer 3

Leads to competition

Question 4

How does variation drive selection?

Answer 4

Creates range of phenotypes

Question 5

What are the types of natural selection?

Answer 5

Directional

Question 6

What is directional selection?

Answer 6

Selects for one extreme phenotype

Question 7

What is stabilising selection?

Answer 7

Selects for average phenotype

Question 8

What is disruptive selection?

Answer 8

Selects for extreme phenotypes

Question 9

What is the effect of directional selection on allele frequency?

Answer 9

Increases allele frequency for one extreme

Question 10

What is the effect of stabilising selection on allele frequency?

Answer 10

Increases average

Question 11

What is the effect of disruptive selection on allele frequency?

Answer 11

Increases multiple extremes

Question 12

What is the effect of directional selection on the normal distribution curve?

Answer 12

Shifts curve towards favored extreme

Question 13

What is the effect of stabilising selection on the normal distribution curve?

Answer 13

Narrows the curve

Question 14

What is the effect of disruptive selection on the normal distribution curve?

Answer 14

Shifts into multiple peaks

Question 15

What is an example of directional selection?

Answer 15

Antibiotic resistance in bacteria

Question 16

What is an example of stabilising selection?

Answer 16

Human birth weights

Question 17

What is an example of disruptive selection?

Answer 17

Bird beaks adapting to different food sources