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Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life forms on Earth. Evolution holds that all species are related and gradually change over generations. [1]
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]
These ideas developed into mutationism, the mutation theory of evolution. [ 29 ] [ 30 ] This held that species went through periods of rapid mutation, possibly as a result of environmental stress, that could produce multiple mutations, and in some cases completely new species, in a single generation, based on de Vries's experiments with the ...
A 2019 review by Svensson and David Berger concluded that "we find little support for mutation bias as an independent force in adaptive evolution, although it can interact with selection under conditions of small population size and when standing genetic variation is limited, entirely consistent with standard evolutionary theory."
A diagram demonstrating mutation and selection Modern biology began in ... differences in phenotype. An example is the ... the theory of evolution by natural ...
In the so-called modern synthesis of the early 20th century, between 1918 and 1930 Ronald Fisher brought together Darwin's theory of evolution, with its insistence on natural selection, heredity, and variation, and Gregor Mendel's laws of genetics into a coherent structure for evolutionary biology. Biologists assumed that an organism was a ...
For example, an ancestral species has the alleles a and b fixed in its population, resulting in all individuals having the aabb genotype. When two descendant populations are separated from each other and each undergo several mutations the allele A can occur in one population while the allele B occurs in the second population. When the two ...
A coherent theory of neutral evolution was first proposed by Motoo Kimura in 1968 [9] and by King and Jukes independently in 1969. [10] Kimura initially focused on differences among species; King and Jukes focused on differences within species. Many molecular biologists and population geneticists also contributed to the development of the ...