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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 heritable traits characteristic of a population over generations.
Evolution is the change in the heritable characteristics of biological populations over successive generations. [1] [2] It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, resulting in certain characteristics becoming more or less common within a population over successive generations. [3]
Natural selection is inherently involved in the process of speciation, whereby, "under ecological speciation, populations in different environments, or populations exploiting different resources, experience contrasting natural selection pressures on the traits that directly or indirectly bring about the evolution of reproductive isolation". [54]
In addition, selection mechanisms are also used to choose candidate solutions (individuals) for the next generation. The biological model is natural selection. Retaining the best individual(s) of one generation unchanged in the next generation is called elitism or elitist selection. It is a successful (slight) variant of the general process of ...
This means that the rules of genetic variation may have a different meaning in the natural case. For instance – provided that steps are stored in consecutive order – crossing over may sum a number of steps from maternal DNA adding a number of steps from paternal DNA and so on.
Natural selection affects only 8% of the human genome, meaning mutations in the remaining parts of the genome can change their frequency by pure chance through neutral selection. If natural selective pressures are reduced, then more mutations survive, which could increase their frequency and the rate of evolution.
The outcome of evolution is not a perfectly designed organism. The end products of natural selection are organisms that are adapted to their present environments. Natural selection does not involve progress towards an ultimate goal. Evolution does not strive for more advanced, more intelligent, or more sophisticated life forms. [25]
Conceptually, "evolutionary theorizing about cultural, social, and economic phenomena" preceded Darwin, [6] but was still lacking the concept of natural selection. Darwin himself, together with subsequent 19th-century thinkers such as Herbert Spencer, Thorstein Veblen, James Mark Baldwin and William James, was quick to apply the idea of selection to other domains, such as language, psychology ...