Dobzhansky, Theodosius Grigorievich

Japanese: ドブジャンスキー（英語表記）Dobzhansky， Theodosius Grigorievich

Born January 25, 1900, Nemirov, Russia
[died] December 19, 1975. Davis, California. American geneticist born in Russia. His father was a mathematics teacher. He studied at Kiev University (1917-21). He taught genetics as an assistant professor at Leningrad University (24-27), and then moved to the United States in 1927. He worked under T. Morgan at Columbia University. The following year, he joined Morgan at the California Institute of Technology, where he became a professor (36-40). He was a professor at Columbia University (40-62). He was a professor at the Rockefeller Institute (62-71). He was a professor at the University of California (71). In the 1920s, a group of geneticists and mathematicians began to combine C. Darwin's theory of natural selection with Mendelian genetics to create a theory of evolution. Dobzhansky was one of these people, and his book Genetics and the Origin of Species (1937) contributed to the establishment of evolutionary genetics. Previously, it was thought that the majority of individuals belonging to a species have the same gene, called the wild-type gene, and that a mutation in a wild-type gene alone does not result in a change in traits, but that traits only change when two individuals with mutant genes mate to produce an individual with two copies of the gene, and that this individual can become the driving force of evolution if it has a higher ability to adapt to the environment. However, in his experiments with fruit flies, he discovered examples of evolution occurring much more rapidly than the rate of evolution based on this mechanism, and also clarified that traits can change even if there are not two mutations. Based on these facts, he pointed out that if a mutation that is advantageous for survival occurs, it immediately becomes the cause of evolution, that there is no such thing as a universal wild-type gene in a species, and that genes are diverse, and thus established his own original theory of evolution, which had a major impact on research into the genetics of evolution.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

[生]1900.1.25. ロシア，ネミロフ
[没]1975.12.19. カリフォルニア，デービス
ロシア生れのアメリカの遺伝学者。父は数学教師。キエフ大学に学ぶ (1917～21) 。レニングラード大学助教授として遺伝学を講じた (24～27) のち，1927年アメリカに渡る。コロンビア大学の T.モーガンのもとで研究に従事。翌年モーガンについてカリフォルニア工科大学に移り，同大学教授 (36～40) 。コロンビア大学教授 (40～62) 。ロックフェラー研究所教授 (62～71) 。カリフォルニア大学教授 (71) 。 20年代より一群の遺伝学者，数学者たちによって C.ダーウィンの自然選択説とメンデル遺伝学とを組合せて，進化理論をつくり上げようとする試みが開始され，ドブジャンスキーもその一人として，37年に著わした『遺伝学と種の起源』 Genetics and the Origin of Speciesは，進化遺伝学の確立に寄与した。従来，ある種に属する個体の大部分は野生型遺伝子と呼ばれる同一の遺伝子をもつと考えられ，野生型遺伝子に突然変異が起っただけでは形質の変化は現れず，突然変異遺伝子をもつ個体同士の接合によってこの遺伝子を2個保有する個体が生じたときに初めて形質が変化し，この個体が環境へのより高い適応能力をもっている場合に進化の推進力になると考えられていた。ところが，彼はショウジョウバエを用いた実験でこのような機構に基づく進化の速度よりはるかに急速に進化が起る例を発見し，また突然変異が2個そろわなくても形質に変化が現れることを明らかにし，これらの事実から生存に有利な突然変異が起ればそれがただちに進化の原因となること，種に普遍的な野生型遺伝子というものは存在せず，遺伝子は多様であることを指摘して，独自の進化理論を打立て，進化の遺伝学的研究に大きな影響を与えた。

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