Jens Clausen
Encyclopedia
Jens Christen Clausen was a Danish
-American
botanist, geneticist
, and ecologist. He is considered a pioneer in the field of ecological and evolutionary genetics of plants.
, where he studied botany
, genetics
and ecology
. Christen Raunkiær
suggested he undertake graduate studies and Clausen chose to study the genetics and ecology of the plant family Violaceae
. He studied hybridization patterns across a range of environments and described introgression
of genes between species. He completed his masters degree in 1920 and was appointed appointed assistant professor to geneticist Øjvind Winge
at the Royal Veterinary and Agricultural College
in Copenhagen.
In 1926, Clausen was awarded his PhD for his work on Violaceae; his monograph was one of the first publications that combined systematics, ecology and genetics for any plant group. In 1927-1928, Clausen received a Rockefeller scholarship to study at the University of California, Berkeley
where he worked on the genetics of the genus Crepis
with E. B. Babcock
. During this time he met Californian botanist Harvey Monroe Hall, who invited Clausen to return to the United States to work on the ecological genetics
of California
n native species. Clausen returned to the U.S.A. in 1931 as a staff member at the Carnegie Institution of Washington's Department of Plant Biology at Stanford, California
. With taxonomist David D. Keck
and physiologist William Hiesey
, he formed the first interdisiplinary effort to combine genetics
, ecology
and systematics
in order to understand the ecological genetics
of the evolution
ary process in California
plants. The project lasted 20 years and they performed some of the classic experiments in plant ecology
, where they looked at species formation across altitudinal gradients using experimental plots at Stanford (near sea level), at Mather (at about 4,600 feet), and at Timberline in the Sierra Nevada (at about 10,000 feet).
Clausen, Keck and Hiesey wrote five books on their work, including Experimental Studies on the Nature of Species. I. Effect of Varied Environments on Western North American Plants published in 1940 and Experimental Studies on the Nature of Species. III. Environmental Responses of Climatic Races of Achillea
in 1948. He produced one additional book about his work based on the Messenger Lectures
he gave at Cornell
and published in 1951 as Stages in the Evolution of Plant Species.
He was elected a member of the National Academy of Sciences
, the American Academy of Arts and Sciences
, and the Royal Swedish Academy of Sciences
; he was also a member of the Botanical Society of America
, and the Society for the Study of Evolution
. He was a fellow of the California Academy of Sciences and of the American Association for the Advancement of Science. He was knighted as knight of Danneborg by Frederick IX of Denmark
. Clausen was a Christian and was a member of the First Baptist Church of Palo Alto.
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
-American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
botanist, geneticist
Geneticist
A geneticist is a biologist who studies genetics, the science of genes, heredity, and variation of organisms. A geneticist can be employed as a researcher or lecturer. Some geneticists perform experiments and analyze data to interpret the inheritance of skills. A geneticist is also a Consultant or...
, and ecologist. He is considered a pioneer in the field of ecological and evolutionary genetics of plants.
Biography
Clausen was born in Eskilstrup, Denmark. His parents were famers and at age 14 he took responsibility for the family farm and was largely educated at home with the assistance of a local school teacher. He studied Mendel's genetics and Darwinian evolutionary theory. In 1913 he entered the University of CopenhagenUniversity of Copenhagen
The University of Copenhagen is the oldest and largest university and research institution in Denmark. Founded in 1479, it has more than 37,000 students, the majority of whom are female , and more than 7,000 employees. The university has several campuses located in and around Copenhagen, with the...
, where he studied botany
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
, genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
. Christen Raunkiær
Christen C. Raunkiær
Christen Christensen Raunkiær was a Danish botanist, who was a pioneer of plant ecology. He is mainly remembered for his scheme of plant strategies to survive an unfavourable season and his demonstration that the relative abundance of strategies in floras largely corresponded to the Earth's...
suggested he undertake graduate studies and Clausen chose to study the genetics and ecology of the plant family Violaceae
Violaceae
Violaceae are a family of flowering plants consisting of about 800 species in 21 genera. It takes its name from the genus Viola, the violets and pansies.Older classifications such as the Cronquist system placed Violaceae in an order named after it, the Violales...
. He studied hybridization patterns across a range of environments and described introgression
Introgression
Introgression, also known as introgressive hybridization, in genetics is the movement of a gene from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species...
of genes between species. He completed his masters degree in 1920 and was appointed appointed assistant professor to geneticist Øjvind Winge
Øjvind Winge
Øjvind Winge was a Danish biologist and a pioneer in yeast genetics.He was born in the city of Aarhus in Jutland, the mainland of Denmark. After completing secondary school he travelled to the University of Copenhagen to study law but found himself more suited to the biological sciences into which...
at the Royal Veterinary and Agricultural College
University of Copenhagen Faculty of Life Sciences
The faculty previously known as the Royal Veterinary and Agricultural University is located in Frederiksberg, Denmark and was established in 1856. As of 1 January 2007, the University merged with the University of Copenhagen...
in Copenhagen.
In 1926, Clausen was awarded his PhD for his work on Violaceae; his monograph was one of the first publications that combined systematics, ecology and genetics for any plant group. In 1927-1928, Clausen received a Rockefeller scholarship to study at the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
where he worked on the genetics of the genus Crepis
Crepis
Crepis, commonly known in some parts of the world as hawksbeard or hawk's-beard , is a genus of about 200 annual and perennial flowering plants of the family Asteraceae superficially resembling the dandelion, the most conspicuous difference being that Crepis usually has branching...
with E. B. Babcock
E. B. Babcock
Ernest Brown Babcock was an United States plant geneticist. His pioneering work on the genetics of the genus Crepis and his more than 100 published articles explaining plant evolution primarily in terms of genetics mark him as a pioneer in the application of genetics research.- References :*...
. During this time he met Californian botanist Harvey Monroe Hall, who invited Clausen to return to the United States to work on the ecological genetics
Ecological genetics
Ecological genetics is the study of genetics in natural populations.This contrasts with classical genetics, which works mostly on crosses between laboratory strains, and DNA sequence analysis, which studies genes at the molecular level....
of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
n native species. Clausen returned to the U.S.A. in 1931 as a staff member at the Carnegie Institution of Washington's Department of Plant Biology at Stanford, California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
. With taxonomist David D. Keck
David D. Keck
David Daniel Keck was an American botanist who was notable for his work on angiosperm taxonomy and genetics....
and physiologist William Hiesey
William Hiesey
William McKinley Hiesey was an American botanist who specialized in ecological physiology. He was notable for his collaboration with Jens Clausen and David D. Keck at Stanford University in the 1930s...
, he formed the first interdisiplinary effort to combine genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
, ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and systematics
Systematics
Biological systematics is the study of the diversification of terrestrial life, both past and present, and the relationships among living things through time. Relationships are visualized as evolutionary trees...
in order to understand the ecological genetics
Ecological genetics
Ecological genetics is the study of genetics in natural populations.This contrasts with classical genetics, which works mostly on crosses between laboratory strains, and DNA sequence analysis, which studies genes at the molecular level....
of the evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
ary process in California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
plants. The project lasted 20 years and they performed some of the classic experiments in plant ecology
Plant ecology
Plant ecology is a subdiscipline of ecology which studies the distribution and abundance of plants, the interactions among and between members of plant species, and their interactions with their environment...
, where they looked at species formation across altitudinal gradients using experimental plots at Stanford (near sea level), at Mather (at about 4,600 feet), and at Timberline in the Sierra Nevada (at about 10,000 feet).
Clausen, Keck and Hiesey wrote five books on their work, including Experimental Studies on the Nature of Species. I. Effect of Varied Environments on Western North American Plants published in 1940 and Experimental Studies on the Nature of Species. III. Environmental Responses of Climatic Races of Achillea
Achillea
Achillea is a genus of about 85 flowering plants, in the family Asteraceae, commonly referred to as yarrow. They occur in Europe and temperate areas of Asia. A few grow in North America. These plants typically have frilly, hairy, aromatic leaves....
in 1948. He produced one additional book about his work based on the Messenger Lectures
Messenger Lectures
The Messenger Lectures are a prestigious series of talks given by leading scholars and public figures at Cornell University. They were founded in 1924 by a gift from Hiram Messenger and are regarded as one of the most important of Cornell's extracurricular activities.There were initially "twelve...
he gave at Cornell
Cornell University
Cornell University is an Ivy League university located in Ithaca, New York, United States. It is a private land-grant university, receiving annual funding from the State of New York for certain educational missions...
and published in 1951 as Stages in the Evolution of Plant Species.
He was elected a member of the National Academy of Sciences
United States National Academy of Sciences
The National Academy of Sciences is a corporation in the United States whose members serve pro bono as "advisers to the nation on science, engineering, and medicine." As a national academy, new members of the organization are elected annually by current members, based on their distinguished and...
, the American Academy of Arts and Sciences
American Academy of Arts and Sciences
The American Academy of Arts and Sciences is an independent policy research center that conducts multidisciplinary studies of complex and emerging problems. The Academy’s elected members are leaders in the academic disciplines, the arts, business, and public affairs.James Bowdoin, John Adams, and...
, and the Royal Swedish Academy of Sciences
Royal Swedish Academy of Sciences
The Royal Swedish Academy of Sciences or Kungliga Vetenskapsakademien is one of the Royal Academies of Sweden. The Academy is an independent, non-governmental scientific organization which acts to promote the sciences, primarily the natural sciences and mathematics.The Academy was founded on 2...
; he was also a member of the Botanical Society of America
Botanical Society of America
The Botanical Society of America represents professional and amateur botanists, researchers, educators and students in over 80 countries of the world...
, and the Society for the Study of Evolution
Society for the Study of Evolution
The Society for the Study of Evolution is a professional organization of evolutionary biologists. It was formed in the United States in 1946 to promote evolution and the integration of various fields of science concerned with evolution and to organize the publication of a scientific journal to...
. He was a fellow of the California Academy of Sciences and of the American Association for the Advancement of Science. He was knighted as knight of Danneborg by Frederick IX of Denmark
Frederick IX of Denmark
Frederick IX was King of Denmark from 20 April 1947 until his death on 14 January 1972....
. Clausen was a Christian and was a member of the First Baptist Church of Palo Alto.