Editing Natural selection (section)

{{Short description|Mechanism of evolution by differential reproduction}}
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[[File:Mutation and selection diagram (2).svg|thumb|A diagram demonstrating [[mutation]] and [[Selection (biology)|selection]]]]
{{Evolutionary biology}}

'''Natural selection''' is the differential survival and reproduction of individuals due to differences in [[phenotype]]. It is a key mechanism of [[evolution]], the change in the [[Heredity|heritable traits]] characteristic of a [[population<!--key concept in Darwinian biology-->]] over generations. [[Charles Darwin]] popularised the term "natural selection", contrasting it with [[selective breeding|artificial selection]], which is intentional, whereas natural selection is not.

[[Genetic diversity|Variation]] of traits, both [[Genotype|genotypic]] and phenotypic, exists within all populations of [[organism]]s. However, some traits are more likely to facilitate [[survival]] and [[reproductive success]]. Thus, these traits are passed {{not a typo|on to}} the next generation. These traits can also become more [[Allele frequency|common within a population]] if the environment that favours these traits remains fixed. If new traits become more favoured due to changes in a specific [[Ecological niche|niche]], [[microevolution]] occurs. If new traits become more favoured due to changes in the broader environment, [[macroevolution]] occurs. Sometimes, [[Speciation|new species can arise]] especially if these new traits are radically different from the traits possessed by their predecessors.

The likelihood of these traits being 'selected' and passed down are determined by many factors. Some are likely to be passed down because they [[Adaptation|adapt]] well to their environments. Others are passed down because these traits are actively preferred by mating partners, which is known as [[sexual selection]]. Female bodies also prefer traits that confer the lowest cost to their reproductive health, which is known as [[fecundity selection]].

Natural selection is a cornerstone of modern [[biology]]. The concept, published by Darwin and [[Alfred Russel Wallace]] in a [[On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection|joint presentation of papers in 1858]], was elaborated in Darwin's influential 1859 book ''[[On the Origin of Species|On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life]]''. He described natural selection as analogous to artificial selection, a process by which animals and plants with traits considered desirable by human breeders are systematically favoured for reproduction. The concept of natural selection originally developed in the absence of a valid theory of heredity; at the time of Darwin's writing, science had yet to develop modern theories of genetics. The union of traditional [[Darwinism|Darwinian evolution]] with subsequent discoveries in [[classical genetics]] formed the [[Modern synthesis (20th century)|modern synthesis of the mid-20th century]]. The addition of [[molecular genetics]] has led to [[evolutionary developmental biology]], which explains evolution at the molecular level. While genotypes can slowly change by random [[genetic drift]], natural selection remains the primary explanation for [[Adaptation|adaptive evolution]].