State Darwin's view on the role of variations in evolution.

(N/A) Darwin was influenced by Thomas Malthus's work on populations. Natural selection is based on certain observations that are factual. For example,natural resources are limited,population size is stable (except for seasonal fluctuations),members of a population vary in characteristics even though they look superficially similar (in fact,no two individuals are identical),and most of these variations are heritable.
If these facts are true,and if every organism reproduces at its maximum rate,the population would theoretically grow exponentially (as seen in bacterial growth). Since it is a fact that population size is limited,it implies that there is competition for resources. Some individuals survived and thrived at the cost of others,while some could not.
Darwin's novelty and brilliant insight was this: He asserted that variations which are heritable and make resource utilization better for an individual (making them better adapted to their habitat) enable only those individuals to reproduce and leave more progeny. Hence,over many generations,those survivors will produce more offspring and cause a change in the characteristics of the population,eventually resulting in the evolution of a new form.