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The modern evolutionary synthesis (known as the new synthesis, the modern synthesis, the evolutionary synthesis, millennium synthesis or the neo-Darwinian synthesis) is a 20th-century synthesis of ideas from several fields of biology that provides an account of evolution which is widely accepted.〔: "The scientific consensus around evolution is overwhelming."〕 The synthesis, produced between 1936 and 1947, reflects the consensus about how evolution proceeds.〔 The previous development of nineteenth century evolutionary ideas by Charles Darwin, Gregor Mendel and others and the population genetics, between 1918 and 1932, was a stimulus, as it showed that Mendelian genetics was consistent with natural selection and gradual evolution. The synthesis is still, to a large extent, the current paradigm in evolutionary biology. The modern synthesis solved difficulties and confusions caused by the specialisation and poor communication between biologists in the early years of the 20th century. At its heart was the question of whether Mendelian genetics could be reconciled with gradual evolution by means of natural selection. A second issue was whether the broad-scale changes (macroevolution) seen by palaeontologists could be explained by changes seen in local populations (microevolution). The synthesis included evidence from biologists, trained in genetics, who studied populations in the field and in the laboratory. These studies were crucial to evolutionary theory. The synthesis drew together ideas from several branches of biology which had become separated, particularly genetics, cytology, systematics, botany, morphology, ecology and paleontology. Julian Huxley invented the term in his 1942 book, ''Evolution: The Modern Synthesis''. Major figures in the modern synthesis include Ronald Fisher, Theodosius Dobzhansky, J. B. S. Haldane, Sewall Wright, E. B. Ford, Ernst Mayr, Bernhard Rensch, Sergei Chetverikov, George Gaylord Simpson, and G. Ledyard Stebbins. ==Summary of the modern synthesis== The modern synthesis bridged the gap between the work of experimental geneticists and naturalists, and paleontologists. It states that: #All evolutionary phenomena can be explained in a way consistent with known genetic mechanisms and the observational evidence of naturalists. #Evolution is gradual: small genetic changes regulated by natural selection accumulate over long periods. Discontinuities amongst species (or other taxa) are explained as originating gradually through geographical separation and extinction. This theory contrasts with the saltation theory of William Bateson (1894). #Natural selection is by far the main mechanism of change; even slight advantages are important when continued. The object of selection is the phenotype in its surrounding environment. #The role of genetic drift is equivocal. Though strongly supported initially by Dobzhansky, it was downgraded later as results from ecological genetics were obtained. #Thinking in terms of populations, rather than individuals, is primary: the genetic diversity existing in natural populations is a key factor in evolution. The strength of natural selection in the wild is greater than previously expected; the effect of ecological factors such as niche occupation and the significance of barriers to gene flow are all important. #In palaeontology, the ability to explain historical observations by extrapolation from microevolution to macroevolution is proposed. Historical contingency means explanations at different levels may exist. Gradualism does not mean constant rate of change. The idea that speciation occurs after populations are reproductively isolated has been much debated. In plants, polyploidy must be included in any view of speciation. Formulations such as 'evolution consists primarily of changes in the frequencies of alleles between one generation and another' were proposed rather later. The traditional view is that evolutionary developmental biology (evo-devo) played little part in the synthesis, but an account of Gavin de Beer's work by Stephen J. Gould suggests he may be an exception. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Modern evolutionary synthesis」の詳細全文を読む スポンサード リンク
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