Tuesday, December 06, 2005

The Greats of Evolutionary Genetics

I often reference the classic minds of evolutionary genetics (Dobzhanksy, Wright, and others), but I tend to leave off one of the most important geneticist of them all, H.J. Muller. Thankfully, James Crow has published an short biography of Muller in Nature Reviews Genetics focusing on Muller's contribution to evolutionary biology.
"Although Hermann Joseph Muller is best remembered for his discovery that X-irradiation induces genetic mutations, for which he won the Nobel Prize, he made many influential contributions to evolutionary biology. Muller was the first to emphasize a gene-centred view of evolution, and he made both experimental and theoretical contributions to our understanding of speciation. He also reached insightful conclusions about how genes interact, how they are acted on by natural selection, and how their evolution is influenced by sexual reproduction and population structure. His influence on genetics and evolution was therefore substantial and wide ranging . . . In fact, Muller's interest in evolution pervaded his entire career."
Muller began his career in Thomas Hunt Morgan's lab at Columbia working with Sturtevant and Bridges. While Sturtevant is best known for constructing the first genetic map, Muller is best known for understand the physical nature of chromosomes. Muller received his Nobel prize for his work on X-irradiation and mutation, but he also made other discoveries regarding the homology of chromosomes. He showed that the chromosome arms in Drosophila have the same genes (are homologous) between multiple species. For this discovery, the chromosome arms are known as "Muller's Elements".

Some of Muller's other contributions to evolutionary genetics include:
  • The importance of duplicate genes (through examination of the Bar locus)
  • The importance of sexual reproduction in reducing genetic load (Muller's Ratchet)
  • A multi-locus model for the speciation via hybrid incompatibility factors (Dobzhansky-Muller incompatibilities)
I feel like I should also include some of the low-lights of Muller's career. He spent a lot of time bouncing around between academic institutions. He left the United States in 1932 (his communist beliefs conflicted with the current social environment) for Germany, only to see the rise of Hitler's Nazi party less than one year later. This led to a move to Russia, where research on evolutionary biology was stagnated by Lysenkoism. Eventually, he returned to America, but had difficulty finding a faculty position.
"Having been to Russia, he was branded as a communist, and having spoken out against Lysenko, he was branded as a fascist. With wry amusement, he once said that at least both could not be true."
Eventually, Muller was hired by Indiana University in 1945, and earned his Nobel prize in 1946. His work is some of the most important in both genetics and evolutionary biology. If you have access to the Nature publications, I suggest you read the entire article -- Crow tells both a human story and the story of a scientist.


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