Natural selection

:For the computer game, see Natural Selection (computer game).

Overview

The basic concept of natural selection is that conditions (or "nature") determine (or "select") how well particular traits of organisms can serve the survival and reproduction of the organism; organisms lacking these traits might die before reproducing, or be less prolific. As long as environmental conditions remain the same, or similar enough that these traits continue to be adaptive, such traits will become more common within populations. Loss of the species' ecological niche or crowding-out due to population growth can change drastically the adaptive traits required to survive—in such conditions, or in any circumstance where survival is determined by ecology more than by the secondary sexual characteristics, an ecological selection is taking place (this term is used solely to differentiate processes irrelevant to mating, and is of modern usage, having grown up with the field of ecology itself).

Related Topics:
Ecological niche - Population growth - Ecological selection - Ecology

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Darwin's scientific theory of the evolution of species through natural selection starts from the premise that an organism's traits vary in a nondeterministic way from parent to offspring, a process Darwin called "individuation". This theory does not make any specific claims as to how this process works, although more recent scientific

Related Topics:
Evolution - Species - Nondeterministic

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discoveries in genetics explain several mechanisms that occur in the process of reproduction: in the case of both asexual and sexual reproduction, random mutation (including DNA transcription errors); in the case of sexual reproduction (which mixes the DNA of two parents into an offspring), gene flow and genetic drift are also important mechanisms. Competition (typically among males to impregnate females) for mates produces sexual selection—a process which Darwin considered secondary to ecological in most species.

Related Topics:
Genetics - DNA - Transcription - Gene flow - Genetic drift - Sexual selection

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Natural selection does not distinguish between ecological selection and sexual selection, as it is concerned with traits, for example, dexterity of movement, on which both may operate simultaneously. If a particular variation makes the offspring which manifest it better suited to survival or to successful reproduction, that offspring and its descendants will be more likely to survive than those offspring without the variation. The original traits, as well as any maladaptive variations, will disappear as the offspring who carry them are replaced by their more successful relatives.

Related Topics:
Ecological selection - Sexual selection

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Therefore, certain traits are preserved due to the selective advantage they provide to their holders, allowing the individual to leave more offspring than individuals without the trait(s). Eventually, through many iterations of this process, organisms will develop more and more complex adaptive traits.

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