Modern evolutionary synthesis |
The modern evolutionary synthesis (often referred to simply as the modern synthesis) brings
together Charles Darwin's theory of the evolution of species by natural selection with Gregor Mendel's
theory of genetics as the basis for biological inheritance. Major figures in the
development of the modern synthesis include Ronald Fisher, Theodosius Dobzhansky, J.B.S. Haldane, Sewall Wright, Julian Huxley, Ernst Mayr, and
George Gaylord Simpson.
History
Mendelian genetics was rediscovered in 1900. However, there
were differences of opinion as to what was the variation that natural selection acted upon. The biometric school, led by Karl Pearson followed Darwin's idea that small differences were important for
evolution. The Mendelian school, led by William Bateson, however
thought that Mendel's work gave an evolutionary mechanism with large differences.
This issue was finally resolved by Ronald Fisher, who in 1918 produced a
paper entititled On the correlation between relatives on the supposition of Mendelian inheritance, which showed using a
model how discontinuous variation could be the result of the action of many loci. This is
generally regarded as the starting point of the synthesis.
Tenets of the modern synthesis
According to the modern synthesis as established in the 1930s and 1940s, genetic variation in populations arises by chance through mutation (this is now known to be due to mistakes in DNA replication) and recombination (crossing over of homologous chromosomes
during meiosis). Evolution consists primarily of changes in the frequencies of alleles between one generation and another as a result of
genetic drift, gene flow
and natural selection. Speciation occurs gradually when populations are reproductively isolated by geographic barriers.
Further advances
The modern evolutionary synthesis continued to developed and refined after the initial establishment in the 1930s and 1940s.
The most notable paradigm shift was the so-called Williams
revolution, after George C. Williams presented a
gene-centric view of evolution in the 1960s.
See also: Population genetics
References
- Dobzhansky, T. Genetics and the Origin of Species, Columbia University Press, 1937 ISBN 0-2310-5475-0
- Fisher, R. A. The Genetical Theory of Natural Selection, Clarendon Press, 1930 ISBN 0-1985-0440-3
- Haldane, J. B. S. The Causes of Evolution, Longman, Green and Co., 1932; Princeton University Press reprint,
ISBN 0-6910-2442-1
- Huxley, J. S., ed. The New Systematics, Oxford University Press, 1940 ISBN 0-4030-1786-6
- Huxley, J. S. Evolution: The Modern Synthesis, Allen and Unwin, 1942 ISBN 0-0284-6800-7
- Mayr, E. Systematics and the Origin of Species, Columbia University Press, 1942; Harvard University Press reprint
ISBN 0-6748-6250-3
- Simpson, G. G. Tempo and Mode in Evolution, Columbia University Press, 1944 ISBN 0-2310-5847-0
- Wright, S. 1931. "Evolution in Mendelian populations". Genetics 16: 97-159.
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