natural selection

process in which species that are best adapted to their environments will survive

Natural selection is the process by which favorable traits that are heritable become more common in successive generations of a population of reproducing organisms, and unfavorable traits that are heritable become less common. Natural selection acts on the phenotype, or the observable characteristics of an organism, such that individuals with favorable phenotypes are more likely to survive and reproduce than those with less favorable phenotypes. If these phenotypes have a genetic basis, then the genotype associated with the favorable phenotype will increase in frequency in the next generation. Over time, this process can result in adaptations that specialize organisms for particular ecological niches and may eventually result in the emergence of new species.
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Natural selection n. The process in nature by which, according to Darwin's theory of evolution, only the organisms best adapted to their environment [more]Natural selection - Community and Resources

Noun
1. a natural process resulting in the evolution of organisms best adapted to the environment
(synonym) survival, survival of the fittest, selection
(hypernym) natural process, natural action, action, activity

Natural Selection In Darwinian theory, an important factor in biological evolution. If, for example, a number of animals of one species are exposed to an unduly cold climate, many will die, and the survivors will be the hardier ones. These hardier ones are said to transmit their hardiness to their posterity, whereby the species becomes modified to that extent. A continual succession of such small changes, provoked by changes of environment, was supposed to act cumulatively, thus eventually producing the differences distinguishing one species from another. From this, in combination with other kinds of selection, such as sexual selection, the higher animal types have in the course of ages been derived from the lower.
The theory is open to grave objections on several grounds. There is a complete lack of evidence of the existence of any such permanently cumulative effect; further, such variations are temporary, and procreation tends to a reversion to the standard type as soon as the environmental influence is withdrawn. Again, such a process would tend to produce the greatest diversity and divergence among the species, each variety differentiating more and more widely in its own special direction, without any tendency toward a mounting scale of perfection from ameba to man.
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