Fitness is the end result of the ability to adapt and get selected by Nature. Explain with suitable example.

Explanation

Fitness is based on certain characteristics which are inherited and the ability to adapt to the changing environment. It is the end result of adaptation because a fit individual survives and unfit individuals are eliminated from the population.
Individuals continuously complete with each other in a population for food, space and light. The one which is better adapted and naturally selected by nature survives and reproduces.
For Example, Industrial Evidence : It is a natural selection. In england, it was observed before industrialisation that white-winged moth were more than dark-winged moth. But the situation became reversed after industrialisation. It was found that predators will spot and pick a moth against a contrasting background. During pre-industrialisation, the tree trunks were covered by white lichens and on white-background dark coloured moth can be picked up.
During post industrialisation, the tree trunks were covered by dark-winged or melanised mouth and during the process the trunks were covered by dark, dust, coal particles and became dark, on which white moth can easily be picked up. Thus, it was found that industrial melanism supports evolution by natural selection.