(N/A) Darwinian selection theory states that individuals with favourable variations are better adapted than individuals with less favourable variations.
Nature selects individuals with useful variations because these individuals are better evolved to survive in the existing environment.
An example of such selection is antibiotic resistance in bacteria.
When a bacterial population is grown on an agar plate containing the antibiotic penicillin,the colonies that are sensitive to penicillin die,whereas one or a few bacterial colonies that possess resistance to penicillin survive.
This survival occurs because these specific bacteria underwent a chance mutation,which resulted in the evolution of a gene that confers resistance to the penicillin drug.
Consequently,the resistant bacteria multiply quickly compared to the non-resistant (sensitive) bacteria,thereby increasing their population.
Thus,the advantage of one individual over others helps in the struggle for existence,illustrating the process of natural selection.