Question

In the pre-industrialised environment of England, the light coloured moths were able to camouflage with the bark of trees due to the growth of ________ on the trees.

• A. lichens
• B. mosses
• C. ferns
• D. conifers

Answer 1

The correct option is A lichens

Lichens grow in pollution free environments. They are often used as an indicator of pollution as they are very sensitive to SO${}_2$. Before industrialisation in England, it was observed that there were more light-winged peppered moths (Biston betularia) on trees than dark-winged or melanised moths (Biston carbonaria). In that period, the bark of the trees was occupied by the lichens. This led to the tree trunks to be light colored. The light color of the moths conferred them a survival advantage by camouflaging them in the light colored background of lichens growing on the bark of trees.

Figure: Light-winged peppered moth and dark-winged peppered moth on lichens