MAYR, ERNST

(b. July 5, 1904, Kempten, Ger.), German-born American biologist known for his work in avian taxonomy, population genetics, and evolution. Two years after receiving the Ph.D. degree from the University of Berlin (1926), Mayr, then a member of the university staff, led the first of three expeditions to New Guinea and the Solomon Islands, where he was profoundly impressed with the effects of geographic distribution among various animal species. His early studies of the ability of one species to separate or subdivide into daughter species (speciation) and of those populations that were established by a small number of founders (founder populations) made him one of the leaders in the development of the modern synthetic theory of evolution. This theory encompasses the biological processes of gene mutation and recombination, changes in the structure and function of chromosomes, reproductive isolation, and natural selection. Mayr continued his studies as the curator of birds at the American Museum of Natural History in New York (193253), where he wrote more than 100 papers on avian taxonomy, including Birds of the Southwest Pacific (1945). He proposed in 1940 a definition of species that won wide acceptance in scientific circles and led to the discovery of a number of previously unknown species. In 1953 he became Alexander Agassiz professor of zoology at Harvard University and in 1961 became director of the Museum of Comparative Zoology, retiring in 1970. His works include Methods and Principles of Systemic Zoology (with E.G. Linsley and R.L. Usinger; 1953), Animal Species and Evolution (1963), and The Growth of Biological Thought (1982).