Selection

Question 1

When does stabilising selection happen

Answer 1

When the environment stays the same

Question 2

What happens in stabilising selection

Answer 2

The graph becomes narrow spread but mean stays the same.
Extreme phenotype a eliminated
Individuals near the mean are favoured and can pass on advantageous allele
Individuals with extreme phenotype less likely to pass on their allele

Question 3

What happens in directional selection

Answer 3

Phenotype of one extreme selected for Nd the other extreme is against.
The mean moves in the direction of individuals with the advantageous allele and survive.

Question 4

Why is there a decrease in a certain population in a species

Answer 4

There is variation due to mutations in the alleles (context to exam question)
Some (context) have allele to survive and live in (context)
There is differential reproductive success and adapted organisms can pass on advantageous allele
Increase in advantageous allele
Decrease in non advantageous allele

Question 5

When does directional selection happen

Answer 5

When the environment changes