Question

In a particular population of mice that lives in the Southwestern United States, there are two fur color variants: black and light brown. The black fur is a dominant trait in these mice. The population described lives in an area dominated by dark-colored rock and that is populated by owls that prey upon mice that do not blend into the environment. The frequency of the black fur allele in this particular population is 0.6.
If the rock were to become covered by sand dunes, what change in the population would you predict?

• A. The frequency of the dark fur color would increase.
• B. The frequency of the light fur color would decrease.
• C. The frequency of the dark fur color would decrease.
• D. The frequency of the allele for fur color would remain the same.
• E. The allele .frequencies for dark and light fur color would become equai.

Answer 1

The correct option is B The frequency of the light fur color would decrease.

Black fur mice is dominant in the area as it can escape the owls by blending with the dark-coloured rocks. If the rock will get covered by sand dunes, then light fur mice will be able to escape the owls and predominate in the area as they will be able to blend with the environment but the dark fur mice will be unable to do this. Hence, dark fur mice will be eaten by the owls and light fur mice will predominate in the area. This is in accordance with Darwin's natural selection that as a struggle for existence, only those organisms could survive which have favourable variation to adapt with the environmental conditions. In other words, struggle for existence results in survival of the fittest which means that natural selection tends to favour those organisms which are most fit to survive with the reproductive age in a particular environment and to produce offspring.

Hence, the frequency of mice having light fur will increase.

So, the correct answer is 'The frequency of the light fur color would increase'.