Question

In rock pocket mice, a mutation in the gene for fur colour results in black fur instead of the brown fur found in mice without mutation. This mutation causes the mice to be more visible in areas of scrub.
Which description best fits our understanding of how phenotypic mutations affect populations?
a) The mice with the black fur mutation will be unlikely to survive and will disappear over time.
b) The black fur mutation will probably become very common in areas of scrub.
c) The black fur mutation might not be successful in scrub areas, but might be successful in areas with dark terrain.
d) The black fur mutation will probably continue to appear at the same frequency in all environments.

Answer 1

According to the theory of natural selection, it was mentioned that the organism which is fitter and adapts fully to its new surroundings and passes on the necessary genes to its next-generation would only survive and the rest species would get destroyed.

Complete answer:
The mutations caused in the rock pocket mice, was of the fur colour changing from brown to black. The mice with brown fur cover easily camouflaged themselves on the scrub making them not visible to the predators. But the black fur mice were visible to the predators due to their dark fur colour which wasn’t able to camouflage on the scrub surfaces. Hence making them easy prey of the predators. This led to the decrease in the population of the black fur mice to a level where no black fur mice were spotted later on. This led to the natural selection of the brown fur mice as they were well suited and adapted to the surroundings. According to the theory, only the fittest of the varied species would survive and the brown fur mice were the fittest as they were able to camouflage from their predators and the black fur mice developed desirable mutation which needed to be passed on to the next generation.

So, the answer is option A, ‘the mice with the black fur mutation would unlikely survive and would disappear over time’.

Note:
The selection of the fittest is the way one organism leads to its evolution to a better adaptable species. Such can be seen in the example of industrial melanism where the colour of the moths changes according to their surroundings.