Some Biogeographers, Evolutionists and Ecologists:
Chrono-Biographical Sketches

Clausen, Jens Christen (Denmark-United States 1891-1969)
ecological genetics, botany

In the history of ecological genetics studies, Jens Clausen stands as an important pioneer. As the DSB relates: "[Clausen and his team used] the technique of cloning plants belonging to several species in distantly related genera and growing clonal divisions in three gardens...at Stanford, at Mather, and at Timberline (the latter two in the Sierra Nevada, at 4,600 and 10,000 feet, respectively). The results of this research, published in 1940, showed clearly that adaptation to different altitudes and climates had been accompanied in each species by profound changes that established a series of genetically different races or ecotypes." Clausen and his team continued with this same general research approach to produce additional important findings (especially as related to the speciation process in plants), the general conclusions from which are summarized in his 1951 book Stages in the Evolution of Plant Species.

--born in Eskilstrup, Denmark, on 11 March 1891.
--1913-1920: studies botany, ecology and genetics at the University of Copenhagen
--1916-1918: serves in the Danish army
--1920: M.S. in genetics, University of Copenhagen
--1921: made assistant at the Royal Agricultural College, Copenhagen
--1926: Ph.D., University of Copenhagen
--1927-1928: Rockefeller fellow, California
--1931: moves to the United States
--1931-1969: holds research appointment in the division of plant biology, Carnegie Institution of Washington, Stanford, California
--1940: publishes his Experimental Studies on the Nature of Species. I. Effect of Varied Environments on Western North American Plants, with D. D. Keck and W. M. Hiesey
--1943: becomes naturalized citizen of U.S.
--1948: publishes his Experimental Studies on the Nature of Species. III. Environmental Responses of Climatic Races of Achillea, with D. D. Keck and W. M. Hiesey
--1948: receives the Mary Soper Pope medal of botany
--1951-1956: professor of biology, Stanford University
--1951: publishes his Stages in the Evolution of Plant Species
--1956: president, Society for the Study of Evolution
--1956: awarded the Botanical Society of America's certificate of merit
--1957: honorary Ph.D. in agronomy, University of Uppsala
--1959: elected to the National Academy of Sciences
--1961: elected to the American Academy of Arts and Sciences; knighted by King Frederick IX of Denmark
--dies at Palo Alto, California, on 22 November 1969.