Looking for classes? Ksquare Career Institute, Bengaluru →
In the case of peppered moth ($Biston\ betularia$) the black-coloured form became dominant over the light-coloured form in England during industrial revolution. This is an example of
A
Inheritance of darker colour character acquired due to the darker environment
B
Natural selection whereby the darker forms were selected
C
Appearance of the darker coloured individuals due to very poor sunlight
D
Protective mimicry
Detailed Solution
Before industrialisation (1850), the tree trunks in England were covered with white lichens; white-winged moths were camouflaged on them and escaped predators, while dark-winged moths were picked out by birds.
After industrialisation (1920), smoke and soot killed the lichens and darkened the tree trunks. Now the white moths were conspicuous and were eaten, while the dark (melanic) moths were camouflaged and survived.
So the proportion of dark moths increased: the predators selected against the conspicuous form. Both forms already existed in the population; the colour was not acquired from the environment.
This is industrial melanism, an example of natural selection.
Hence it is natural selection whereby the darker forms were selected.
After industrialisation (1920), smoke and soot killed the lichens and darkened the tree trunks. Now the white moths were conspicuous and were eaten, while the dark (melanic) moths were camouflaged and survived.
So the proportion of dark moths increased: the predators selected against the conspicuous form. Both forms already existed in the population; the colour was not acquired from the environment.
This is industrial melanism, an example of natural selection.
Hence it is natural selection whereby the darker forms were selected.