The concept of natural selection states that competition for limited resources among a species with varying traits results in a winner and a loser, with the winner having a greater opportunity to survive and breed offspring with like traits. Over time the advantageous traits become predominant in the species.
The existence of variations within a species begins the process of natural selection. The variation may be in either appearance or behavior. The ability of a variation to be inherited by offspring is central to the concept of natural selection. In order to impact future generations over time, the variation must be able to be passed on or it is not a factor in determining future traits of the species.
The varying trait must give the organism an advantage in the quest for resources in its environment in order for natural selection to be in its favor. Advantageous traits are often retained in the species over time, allowing the organism to adapt in a favorable way to local conditions.
Charles Darwin developed the concept of natural selection as a result of his observations as a naturalist on a voyage around the Galapagos Islands. During his voyage he noted the effects of environmental isolation on the various inhabitants of each island.