Question

The evolution of peppered moths in England is an example of
A) Stabilizing selection
B) Directional selection
C) Disruptive selection
D) Genetic drift
E) Convergent evolution

Answer 1

Hint: Peppered moth is an example for the evolution and natural selection by changing its colour. It changed its colour from light to dark as the pollution due to industrial revolution increased. As soon as the pollution decreased, it changed its colour to light. This change is the biggest example supporting Darwin’s theory of natural selection.

Complete answer:
To solve this question, we must know the different types of selection and how it is applicable in case of peppered moths.
A) Stabilizing selection-This type of selection is independent of environmental change. If there is no environmental change, the fit species will not change. This is in-evident in the case of peppered moths.
B) Directional selection- It takes place when there is change in the environment, the pressure is generated on the species to change so that they can survive. As we know that in the case of peppered moth, the colour change was evident due to the environmental factors. Thus, it is an example of directional selection.
C) Disruptive Selection- In this type of selection only extreme values of traits are favoured over the intermediate value. It is the driving force for speciation. It is also an environmental selection but it only favours the extreme traits.
D) Genetic drift- It is the change in the alleles over generation due to chance. It is evident in small populations.
E) Convergent evolution- In this type of evolution, the organisms which have evolved from different ancestors attain or gain similar phenotypic adaptations due to the similar living condition.

The correct answer is B) Directional selection.

Note:
Direction selection can be defined as the selection of a particular extreme phenotype and the other intermediate phenotypes are not supported. In case of disruptive selection, the selection pressure is generated which selects the extreme phenotypes and discards the average traits.