3.4.4 Genetic diversity and adaptation

Question 1

What is genetic diversity?

Answer 1

The number of different alleles of genes in a species or population.

Question 2

Explain how a genetic bottleneck reduces genetic diversity.

Answer 2

• A big reduction in a population…
• …reduces the number of different alleles in the gene pool…
• …and so reduces genetic diversity.

Question 3

Give an example of a behavioural adaptation.

Answer 3

Possums sometimes ‘play dead’ if they’re being threatened by a predator to escape attack.

Question 4

Tawny owls show variation in colour. There are light grey owls and darker brown owls. Before the 1970s there were more grey owls than brown owls in Finland. Since then, climate change has been causing a decrease in the amount of snowfall in Finland. During this period, the darker brown owls have become more common.
Suggest why the brown owls are better adapted to living in an area with less snowfall than the grey owls.
[2 marks]

Answer 4

E.g.

• The brown owls may be better camouflaged/blend in with the landscape better than the grey owls when there’s no snow cover.
• This makes them less likely to be eaten by predators.

Question 5

Tawny owls show variation in colour. There are light grey owls and darker brown owls. Before the 1970s there were more grey owls than brown owls in Finland. Since then, climate change has been causing a decrease in the amount of snowfall in Finland. During this period, the darker brown owls have become more common.
Explain how the brown owls have become more common.
[3 marks]

Answer 5

• The brown owls are more likely to survive and reproduce when there’s less snow cover…
• …and pass on the allele for darker/brown colouring to their offspring.
• Over time, the allele for darker/brown colouring will become more common in the population.