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Industrial melanism as observed in peppered moth proves that
A
the melanic form of the moth has no selective advantage over lighter form in industrial area
B
the lighter-form moth has no selective advantage either in polluted industrial area or non-polluted area
C
melanism is a pollution-generated feature
D
the true black melanic forms arise by a recurring random mutation
Detailed Solution
Before industrialisation in England, the light-coloured form of the peppered moth (Biston betularia) was common, and the dark melanic form was rare.
During the Industrial Revolution, soot from coal-burning factories killed the lichens and darkened the tree trunks. The melanic moths were now camouflaged and escaped predation by birds, while the light moths were picked out; the frequency of the melanic form rose to over 90 percent in polluted areas.
The important point is that the dark form was not created by pollution. It was already present in the population, arising again and again by a random mutation.
Pollution only changed the direction of natural selection, so that the already existing melanic variant was favoured.
So the melanic form does have a selective advantage in industrial areas, the light form has an advantage in non-polluted areas, and melanism is not a pollution-generated feature; those three statements are wrong.
Industrial melanism thus proves that the true black melanic forms arise by a recurring random mutation.
During the Industrial Revolution, soot from coal-burning factories killed the lichens and darkened the tree trunks. The melanic moths were now camouflaged and escaped predation by birds, while the light moths were picked out; the frequency of the melanic form rose to over 90 percent in polluted areas.
The important point is that the dark form was not created by pollution. It was already present in the population, arising again and again by a random mutation.
Pollution only changed the direction of natural selection, so that the already existing melanic variant was favoured.
So the melanic form does have a selective advantage in industrial areas, the light form has an advantage in non-polluted areas, and melanism is not a pollution-generated feature; those three statements are wrong.
Industrial melanism thus proves that the true black melanic forms arise by a recurring random mutation.