Genetics and the origin of species: an introduction.

Abstract

Theodosius Dobzhansky (1900–1975) was a key author of the Synthetic Theory of Evolution, also known as the Modern Synthesis of Evolutionary Theory, which embodies a complex array of biological knowledge centered around Darwin’s theory of evolution by natural selection couched in genetic terms. The epithet “synthetic” primarily alludes to the artful combination of Darwin’s natural selection with Mendelian genetics, but also to the incorporation of relevant knowledge from biological disciplines. In the 1920s and 1930s several theorists had developed mathematical accounts of natural selection as a genetic process. Dobzhansky’s Genetics and the Origin of Species , published in 1937 (1), refashioned their formulations in language that biologists could understand, dressed the equations with natural history and experimental population genetics, and extended the synthesis to speciation and other cardinal problems omitted by the mathematicians. The current Synthetic Theory has grown around that original synthesis. It is not just one single hypothesis (or theory) with its corroborating evidence, but a multidisciplinary body of knowledge bearing on biological evolution, an amalgam of well-established theories and working hypotheses, together with the observations and experiments that support accepted hypotheses (and falsify rejected ones), which jointly seek to explain the evolutionary process and its outcomes. These hypotheses, observations, and experiments often originate in disciplines such as genetics, embryology, zoology, botany, paleontology, and molecular biology. Currently, the “synthetic” epithet is often omitted and the compilation of relevant knowledge is simply known as the Theory of Evolution. This is still expanding, just like one of those “holding” business corporations that have grown around an original enterprise, but continue incorporating new profitable enterprises and discarding unprofitable ones. Darwin summarized the theory of evolution by natural selection in the Origin of Species (2) as follows: “As many more individuals are produced than can possibly survive, there must in every case …