Types of selection

Question 1

Selection

Answer 1

The process by which organisms that are better adapted to the environment survive to breed and pass on the favourable alleles to the subsequent generations

Question 2

Types of selection

Answer 2

Directional
Stabilising
Disruptive

Question 3

What is directional selection

Answer 3

Organisms with a phenotype to left or right of the mean phenotype survive and reproduce
Pass on most favourable alleles to offspring
Mean will move more to left or right

Question 4

What is stabilising selection

Answer 4

Extreme phenotypes are both unfavourable, so phenotypes closest to the mean age more likely to survive, breed and pass on offspring

Question 5

What environmental factors can exert selection pressure and change allele abundance

Answer 5

Predators
Availability of resource
Nutrient supply
Disease
Accumulation of waste

Phenomena
Abiotic factors (soil pH)
Weather conditions

Question 6

What are the 3 characteristics of stabilising selection?

Answer 6

No evolution
Against extreme phenotypes
No environmental change

Question 7

What are the 4 characteristics of directional selection?

Answer 7

Change in environment
Evolution occurs
Favours extreme phenotypes
Selection against 1 extreme phenotype and selection for 1 extreme in the range

Question 8

4 Characteristics of disruptive selection

Answer 8

Involves speciation
Involves environmental change
Involves evolution
Favours both extreme phenotypes, selection against mean

Question 9

What is disruptive selection?

Answer 9

Selection that favours extreme phenotypes at the expense of the mean phenotype. Opposite of stabilising