In England, after industrialisation, dark-winged (melanised) moths became more common than white-winged moths in the same area. This observation supports evolution through which of the following mechanisms?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Natural selection
Natural selection means that individuals better suited to their surroundings survive and leave more offspring, so their type becomes more common. In England, lichens kept tree trunks pale before industrialisation, so white-winged moths were hidden. Later, smoke and soot darkened the trunks, and the dark-winged moths became the hidden ones.
Option (1) Geographical isolation — Incorrect. Geographical isolation is the splitting of a population by a barrier such as a sea or a mountain. Here both kinds of moth lived in the same area; nothing separated them.
Option (2) Mimicry — Incorrect. Mimicry is one species copying the look of another to avoid being eaten. The dark moths did not copy another species; they only matched the dark bark.
Option (3) Natural selection — Correct. Birds that eat moths could easily spot the moths that stood out against the bark. So on dark trunks, the dark-winged moths survived and multiplied. Nature “selected” the better-hidden form, which is natural selection.
Option (4) Artificial selection — Incorrect. Artificial selection is choosing by humans, as in breeding dogs or crops. No person chose which moths survived; predators did.
NCERT Extract:
What are the Evidences for Evolution? – “… Another interesting observation supporting evolution by natural selection comes from England. In a collection of moths made in 1850s, i.e., before industrialisation set in, it was observed that there were more white-winged moths on trees than dark-winged or melanised moths. However, in the collection carried out from the same area, but after industrialisation, i.e., in 1920, there were more dark-winged moths in the same area, i.e., the proportion was reversed.”
What are the Evidences for Evolution? – “… During postindustrialisation period, the tree trunks became dark due to industrial smoke and soots. Under this condition the white-winged moth did not survive due to predators, dark-winged or melanised moth survived.”