Sewall Wright

Sewall Green Wright ( born December 21, 1889 in Melrose (Massachusetts ); † March 3, 1988 in Madison ( Wisconsin)) was an American theoretical biologist and geneticist, who founded the population genetics along with Ronald Fisher and JBS Haldane in the 1920s. He was essential in the theory of genetic drift and inbreeding coefficients. Wright also invented the statistical path analysis and the " fitness landscapes".

Life

Sewall Green Wright was born on December 21, 1889 in Melrose (Massachusetts ). His father Philip Green Wright was a teacher, his mother's name was Elizabeth Quincy Sewall Wright and was a cousin of his father. Sewall had two younger brothers: the later political scientist Quincy Wright and Theodore Paul Wright, who was aviation technician. From Sewall's third year of life the family lived in Galesburg ( Illinois).

Sewall Wright studied natural sciences with an emphasis in zoology at the University of Illinois, where he earned a Master of Science in 1912. He then worked at the geneticist William Ernest Castle at Harvard University and received his doctorate in 1915 with a thesis on the inheritance of coat color in guinea pigs. In 1921 he married Louise Lane Williams ( 1895-1975 ), with whom he had three children.

After receiving his doctorate Wright first worked at the United States Department of Agriculture (USDA ) in Washington, DC. Developed in this time and he published some of his most important ideas. In 1926 he was appointed professor at the University of Chicago, and there he remained until he retired in 1955 at age 65. He then taught for a further 5 years at the University of Wisconsin- Madison.

Wright was physically and mentally very active into old age. He died on 3 March 1988 at the age of 98 years in Madison from the effects of pelvic fracture he had suffered in a fall during a hike.

Work

Already in his dissertation published in 1916 expressed Wright the view that interactions of genetic factors within populations are much more important than the changes (mutations ) of individual genes to be teachers Castle and other important geneticists had been paid mainly. From 1917 he used " as a natural principle " ( Jahn ) already formulated in 1908 by Wilhelm Weinberg and Godfrey Harold Hardy Hardy -Weinberg law, without any knowledge of the publications of these predecessors. This law describes a state of equilibrium in which the relative frequencies of alleles in a population will remain constant if no selection is made.

In the early 1920s, Wright published the concept of the inbreeding coefficient, the newly developed method of path analysis for the interpretation of correlations in complex causal systems and the theory that gradual genetic changes in populations caused by the interaction of inbreeding, crossbreeding and selection. Later he added the concept of genetic drift largely developed by himself. Thus Wright belongs next to Ronald Fisher and JBS Haldane, one of the founders of theoretical population genetics.

Another invention Wrights are the " fitness landscapes". This is to create graphical representations of the fitness ( reproductive success ) of different gene combinations. Valleys in these landscapes mean lower reproductive success of gene combinations, hills represent favorable gene combinations. Natural selection moves the population on the summit of the hill, while incidental movements in other directions are called genetic drift.

Honors

In 1950 he was awarded the John Frederick Lewis Award of the American Philosophical Society. Wright was elected in 1963 as a " Foreign Member " of the Royal Society, in 1980, the Darwin Medal awarded him. He received ten honorary doctorates. Other awards:

Works

  • An Intensive Study of the Inheritance of Color and Other Coat Characters in Guinea- pigs, with Especial Reference to Graded Variations ( 1916)
  • On the Nature of Size Factors (1917 )
  • Color Inheritance in Mammals (1917/1918)
  • Correlation and Causation ( 1921)
  • Systems of Mating ( 1921)
  • The Effects of Inbreeding and Crossbreeding on Guineapigs (1922 )
  • Coefficients of Inbreeding and Relationship (1922 )
  • The Genetical Theory of Natural Selection - A Review (1930 )
  • Evolution in Mendelian Populations (1931 )
  • The Roles of Mutation, Inbreeding, Crossbreeding and Selection in Evolution ( 1932)
  • Evolution and the Genetics of Populations, four volumes (1968-1978)
Madison (Wisconsin) Coefficient of Inbreeding Path analysis (statistics) G. H. Hardy Integrated Authority File
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