Biographical Memoirs Volume 58 (1989) / Chapter Skim
Currently Skimming:
Jens Christian Clausen
Jens Christian Clausen
Pages 74-107
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 75... ...
Working as the head of a plant biology research group at the Carnegie Institution, lens Christian CIausen successfully cIarifiecI for certain species and under certain conditions the question of heredity versus environment so basic to biology. When still a student in Denmark, fens CIausen became interested in the genetics of a wide variety of local violet fount!
|
From page 76... ...
many a famous botanist to the California vegetation of the mountain stations, and many hacT the good fortune, after a strenuous day of fieldwork, to enjoy his warm hospitality at the Mather "Hog Ranch" cabin. In 1959, at the request of one of his stuclents, lens wrote a brief autobiography, which written in his own wordsfortunately preserves for us something of his spirit: CONFESSIONS AND OPINIONS OF AN ECOLOGIST OF SORTS Personal Background Unfortunately, ~ must confess to being born in ~ 89 ~ in the latter part of the nineteenth century.
|
From page 77... ...
As a consequence, ~ never attencled formal high school (or gymnasium as it was called in Denmark) , but at the age of twenty-two presented myself for the entrance examination to Copenhagen University an affair lasting a full month and was admitted.
|
From page 78... ...
~ likewise stucliec! geology during my teens on small private expeditions around} the country anct on a trip to the famous Kinnekulle region in central Sweden, which contained a complete succession of the Cambrian and Silurian deposits.
|
From page 79... ...
· . My original plan had been to go to the Royal Agricultural College in Copenhagen as a preparation for a farming profession.
|
From page 80... ...
Chresten Raunkiaer was my major professor in botany, P Boysen Jensen in plant physiology, and Wilhelm Johannsen in plant physiology and genetics.
|
From page 81... ...
They constitute one of the early approaches to experimental taxonomy, to studies on natural populations, and to the subject of gene introgression. These studies showed that the characters of the two species recombined at their points of contact, and that genes apparently could migrate some distance from the point of contact.
|
From page 82... ...
The field of the new department was to be basic research in genetics and not plant breeding a far-sighted arrangement in an agricultural college. During the following ten years, the genie compositions of many kinds of plants and of the tropical freshwater fish, Lebistes reticulates, were analyzed; the existence of sex chromosomes in several dioecious plant species was ctiscoverecl; it was found that experimentally inducec!
|
From page 83... ...
With the Carnegie Institution of Washington at Stanforcl, 1931 H
|
From page 84... ...
In 1930 ~ was unexpectedly offered a position as cytologist (later biologist) in his new program on experimental taxonomy, after the department of plant biology of the Carnegie Institution was established at Stanford in actdition to the earlier stations in the Sierra Nevada.
|
From page 85... ...
There are, therefore, fewer ecological zones in Europe than in California, and this is reflected in the ecotypic differentiation. A detailed analysis of natural populations and ecotypes in the Achilles millefolium complex was presented in a Carnegie Institution publication in 1948.
|
From page 86... ...
The major lines of this development were sketched in the 195 ~ publication Stages in the Evolution of Specaes. We found that evolutionary differentiation proceeds gradually from the stage of the local population to distinct ecotypes that occupy ecologically (listinct zones, and to distinct ecospecies after partial barriers have evolved that prevent free gene exchange between certain of the ecotypes of the species complex.
|
From page 87... ...
VI. Interspecific Hybrid Derivatives Between Facultatively Apomictic Species of Blue Grasses and Their Responses to Contrasting Environments
|
From page 88... ...
many new facts on the hereditary structure of related ecotypes and on the nature of the gene systems that distinguish such ecotypes. It opened the door to several highly neglected fields, such as the genetic structure of the elementary evolutionary entities, the range of phenotype expression of the same genotype in contrasting environments, and the interrelation among genes, processes, morphological expression, and environment.
|
From page 89... ...
Such a system causes moderate genetic coherence among characteristics of existing ecotypes as long as the environments remain relatively unchanged. On the other hancI, the ecotypes of a species store a great clear of unused or inactive variability that can become releasecl after crossing; accorclingly, the F2s of interecotypic hybrids show consiclerable transgressive segregation.
|
From page 90... ...
Moderate gene migration is possible between contiguous ecotypes and ecospecies, but genetic coherence and natural selection tend to keep them distinct. The Searchfor the Differentiating Processes Recently, the work of the experimental taxonomy group of the Carnegie Institution has entered a new phase by acicIing physiological laboratory research to the transplant and genetic methocl.
|
From page 91... ...
Nobs, and Olle Bjorkman in 1971 as Carnegie Institution of Washington Publication no. 628 entitled: Experimental Studies on the Nature of Species.
|
From page 92... ...
If, however, your definition of ecology implies such a chain of interacting processes, then it has a great future, anct it will probably take a few centuries before we will be able in detail to trace some of the simpler chains of interaction. Depending upon your own preference, you can name this branch of science evolution of living things, experimental taxonomy, biosystematics, genecology, etc., but it is the life sciences of the future.
|
From page 93... ...
. · ~ crossing apomlctlc strains ot grasses originating trom contrasting environments that were unlikely to have crossed in the past might produce variations with new, and possibly fa
|
From page 94... ...
Some of the major contributions of CIausen's group were a thorough basic stucly of various kinds of ecotypes anct their genetic structures, analysis of the composition ant! evolution of native species occurring across contrasting climates in a transect across central California, and an exploration of the possibilities and the limitations of crossing facultatively apomictic species of grasses ant!
|
From page 95... ...
JENS CHRISTIAN CLAUSEN 95 Evolutionary cytogenetics was a young science when CIausen took it up, but his work became a classic example of its possibilities. The results of his investigations anct his noncompetitive joy in doing the work ant!
|
From page 96... ...
96 BIOGRAPHICAL MEMOIRS HONORS AND DISTINCTIONS 1949 Mary Soper Pope Medal of Botany, Cranbrook Institute of S Hence 1956 Certificate of Merit, Botanical Society of America 1956 President, Society for the Study of Evolution 1959 Member, National Academy of Sciences 1959 Royal Danish Academy of Science and Letters 1959 Fellow, California Academy of Science; American Association for the Advancement of Science 1961 Named Knight of Danneborg by King Frederick IX of Denmark 1961 Honorary Fellow, Botanical Society of Edinburgh 1961 American Academy of Arts and Sciences 1961 Royal Swedish Academy of Science
|
From page 97... ...
citizen 1950 Messenger Lectures, Cornell University 1950-1961 Trustee, Berkeley Baptist Divinity School 1951 Professor by Courtesy, Stanford University 1953 Lecturer in Brazilian universities 1956 Retired from Carnegie Institution of Washington ~ {ens preferred the word "pensioned" and kept on working all his life.) 1962 Lecturer, Vanderbilt University 1963 Lecturer, University of Chicago and Washington State University 1963-1964 Visiting Professor of Genetics, University of Califor nia, Davis 1966 Attended 11th Pacific Science Congress in Tokyo 1969 Died in Palo Alto, California, November 22
|
From page 98... ...
1922 Studies on the collective species Viola tricolor L
|
From page 99... ...
245-46. 1930 Inheritance of variegation and of black flower color in Viola tricolor L
|
From page 100... ...
Experimental taxonomy: Madiinae, field and herbarium studies, garden observations, cytology, genetic studies, transplant studies, Zauschneria. Carnegie Inst.
|
From page 101... ...
Experimental taxonomy: Hereditary composition of climatic races, physiological studies, investigations of the Madiinae, studies at the transplant stations. Carnegie Inst.
|
From page 102... ...
Hiesey. Experimental taxonomy: Breeding stock, Poa hybrids, transplant experiments, cytology of range grasses, Achillea studies, future investigations, guest investigators.
|
From page 103... ...
Hiesey. Experimental taxonomy: The range-grass program, climatic races of Potentilla glandulosa, genetic analysis of the climatic races, selection experiment, exploratory crossings.
|
From page 104... ...
Nobs. Experimental taxonomy: Survey of the range grass program, new Poa hybrids.
|
From page 105... ...
Carnegie Institution of Washington Publication no.
|
From page 106... ...
Phenotypic responses to contrasting environments in the genus Poa. In: Scottish Plant Breeding Station Report, pp.
|
From page 107... ...
Washington Yearb., 66:234-42. 1969 Vegetation of the Harvey Monroe Hall natural area.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.