Q. In the case of peppered moth (Biston betularia) the black-coloured form became dominant over the light-coloured form in England during the 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.
Solution :
Correct option : B The fixation of a character is determined by the fitness and survival adaptability it provides to the organisms in a population. This, in turn, depends on the prevailing environmental conditions, whereby individuals with one character will increase in number and others will perish. So, that character will become dominant .In the case of the peppered moth, the change of dominant character from lighter color to darker color occurred as darker color provided the survival advantage in the environment during industrial revolution where black colored soot accumulated on the trees. Hence, the darker color got naturally selected over the lighter color and became dominant .So, the correct answer is ‘Natural Selection whereby the darker forms were selected’.
