Alfred Henry Sturtevant, II

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Alfred Henry Sturtevant, II

Birthplace: Jacksonville, Morgan County, IL, United States
Death: April 05, 1970 (78)
Pasadena, Los Angeles County, CA, United States
Place of Burial: Woods Hole, Barnstable, Massachusetts
Immediate Family:

Son of Alfred Henry Sturtevant, I and Harriet Morse
Husband of Phoebe Curtis Sturtevant
Father of William Curtis Sturtevant; Private and Alfred Henry Sturtevant, III
Brother of Edgar Howard Sturtevant; Helen Morse Tisdale; Charles Alfred Sturtevant; Julian Monson Sturtevant and Bradford Sturtevant

Managed by: Howard Metzenberg
Last Updated:

About Alfred Henry Sturtevant, II

Alfred Henry Sturtevant was an American geneticist. Sturtevant constructed the first genetic map of a chromosome in 1913. Throughout his career he worked on the organism Drosophila melanogaster with Thomas Hunt Morgan. By watching the development of flies in which the earliest cell division produced two different genomes, he measured the embryonic distance between organs in a unit which is called the sturt in his honor. In 1967, Sturtevant received the National Medal of Science.

Sturtevant’s most notable discoveries include the principle of genetic mapping, the first reparable gene defect, the principle of underlying fate mapping, the phenomena of unequal crossing-over, and position effect. His main contributions to science include his analysis of genetic “linkage groups,” which became classical method of chromosome mapping that we still use today. In 1913, he determined that genes were arranged on chromosomes in a linear fashion, like beads on a necklace. He also showed that the gene for any specific trait was in a fixed location (locus).

In his work between 1915 and 1928, Sturtevant determined that genes of Drosophila are arranged in linear order. In 1920, he published a set of three papers under the title “Genetic Studies on Drosophila simulans,” which “proved that two closely related species had newly recurring mutations that were allelic and thus probably identical” (Provine 2). His work also helped to determine genetic role in sexual selection and development and displayed the importance of chromosomal crossing-over in mutations.

One of Sturtevant’s principle contributions was his introduction to the concept that the frequency of crossing-over between two genes could help determine their proximity on a linear genetic map. His experiments determined that the frequency of double crossing over can be used to deduce gene order. He demonstrated this concept by constructing crosses of three segregating genes, called "three-factor crosses". He found that using three genes as opposed to two provided most accurate information about gene order on chromosome. With this system, Sturtevant discovered that double crossing-over occurs at frequency of equal to or less than product of two single crossing over frequencies. He also surmised that unequal crossing-over was possibly a main force of evolution. "Sturtevant... elaborated on these ideas by incorporating the conception of linear arrangement and by constructing the first chromosome map. Double crossing over and interference were deductions that arose from this result" (Sturtevant, An Introduction to Genetics p. 361).

Sturtevant's work on the Drosophila genome enabled geneticists to further map chromosomes of higher organisms, including human beings. His former Caltech research partner George Beadle claimed that modern biochemical genetics stems directly from Sturtevant’s work.

Adapted from Wikipedia on February 25, 2014.

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Alfred Henry Sturtevant, II's Timeline

November 21, 1891
Jacksonville, Morgan County, IL, United States
July 26, 1926
Morristown, NJ, United States
April 5, 1970
Age 78
Pasadena, Los Angeles County, CA, United States
Woods Hole, Barnstable, Massachusetts