Click for next page ( 75


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 74

OCR for page 74
- JENS CHRISTIAN CLAUSEN March ~ 1, 1891-November 22, 1969 BY C. STACY FRENCH OBSERVERS OF NATURE from primitive man to the most enlightenec! modern scientists have long speculatecI on the relative importance of heredity versus environment in the development of living beings. With regarc! to humans the subject is so explosive that many fear to learn more. With regard to plants, however, the issue of development raises no controversy; experiments can be carried out in peace and results interpreted rationally. 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 ver- sus 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! near his home. A farm boy with sharp powers of ob- servation, he had a mind that always aspect why. His interest in living things eventually took him to Copenhagen Univer- sity for his B.Sc. and M.Sc. degrees and, in 1926, the Ph.D. in the new field of genetics, and then to an assistant profes- sorship at the Royal Agricultural College under 0jvincl Wingea scholarly botanist whom the young farmer- student held in consiclerable awe. In the 1920s, while CIausen was making his name with his 75

OCR for page 74
76 BIOGRAPHICAL MEMOIRS studies of Danish vegetation, Harvey Monroe Hall, professor of botany at the University of California, Berkeley, and a re- search associate of the Carnegie Institution, began trans- planting native plants into contrasting environments. Sup- ported by the institution, Hall and two student botanists, William M. Hiesey ant! Davis! D. Keck, concentrated scat- terecl transplants into three gardens with very different en- vironments: one near sea level at Stanford University, one at an elevation of 4,500 feet at Mather on the western edge of Ypsemite National Park, and one at 10,000 feet at Timberline in the High Sierra of Yosemite's far eastern edge. In 1932, Hall invited CIausen to join his group as a geneticist. But a few months after CIausen's arrival, Hall cried, leaving CIausen to take over as the project's director. lens CIausen's vigor and enthusiasm enabled him to spend long hours in the field and made him a natural leader and clelightfu! colleague. A devoted Christian, Jens's faith rein- forcec! a naturally strong character anc! joy in life, never lim- iting his independence of thought. He introclucec! 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 words- fortunately 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. After a younger brother cried when he was five and ~ ten years of age, ~ be- came, essentially, an only child.

OCR for page 74
JENS CHRISTIAN CLAUSEN 77 ~ cannot claim much formal schooling because ~ went through only two grades of a four-gracle, every-other-day country grammar school in Denmark, attending the two up- per gracles of this school between the ages of eight and thir- teen. The principal of the school, who was also the teacher of the two upper classes, had adviser! my father to spare me from attending the beginner's classes by not starting me in school until ~ was past eight. He remained a personal friend of mine as long as he livecI, but ~ must confess that ~ put little effort into the class work. Insteac! ~ clicl considerable extra- curricular reading. The grade school was followed by one year in a private, local secondary school, where ~ was introducer! to the fun- ciamentals of English, German, worm history, physical and natural sciences, anct mathematics. At the age of fourteen ~ left school entirely and took up the farming of my parents' fifteen-acre place. My father tract been a house-builcler clur- ing my early boyhood, and as ~ took over the daily running of the family farm, he resumed his primary interest. Unlike him, ~ hac! no inclination toward the building trade but was highly interested in farming. As a consequence, ~ never at- tencled 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 af- fair lasting a full month and was admitted. Half a year later had my B.Sc. degree at the University. As far as my early education, ~ was largely autodidactic. ~ Earned to read at the age of four using the daily newspaper as a primer and asking my father the meaning of the words. Curiosity was a driving force, and my father, who himself hacl been a quick learner, was a sensible person. My mother had never gone to school but learned at home. Before ~ nor- mally wouIct have started to school, ~ had learned reacting, writing, and basic arithmetic. These skills opened the worIct of books to me, anc! being brought up on a farm ~ also be-

OCR for page 74
78 BIOGRAPHICAL MEMOIRS came familiar with all kinds of living things ancT with farm practices. At various times during the early years one Earned the principles of physics ant! chemistry from everyday ex- periments and had fun constructing primitive microscopes and telescopes. My first introduction to botany was given me at the age of nine by an uncle who owned my mother's 5-acre birthplace in a botanically interesting part of the country, sculptured by high moraines ant] watercourses. My uncle was a farm la- borer on a neighboring larger farm, but he was highly intel- ligent, interested in botany, anc! had by himself learned to recognize most of the Danish wile! plants. T spent short sum- mer vacations there, anct on weekends he took me along on hikes over hill anc! clale and through forests. These trips opened a new world to me. During my early teens, ~ borrowed from the county li- brary Eugenius Warming's recently published book, Plante- samfund, the Danish forerunner of his later, Ecology of Plants, and considerably more inspired than its English successor. ~ became cleeply interested in this subject, anc! during my high school years ~ made a cletailecl study of the botanical com- munities within a 2,000-acre moor area near my home anct wrote a kind of term paper on the subject as part of my botanical training. ~ likewise stucliec! geology during my teens on small pri- vate expeditions around} the country anct on a trip to the famous Kinnekulle region in central Sweden, which con- tained a complete succession of the Cambrian and Silurian deposits. ~ returned from such expeditions with considerable paleontological and botanical loot. My home was also near primitive sites of miclclle stone age kitchen mittens, and near remnants of a neolithic lake-c~weller's community where stone axes of great artistic beauty had been manufactured for trade some 4,000 years ago. The hills were stuclded with

OCR for page 74
JENS CHRISTIAN CLAUSEN 79 burial sites from bronze and early iron age, uniting the past with the present. News of the rediscovery of Menclelism drifter! through the local newspapers, and in high school ~ also bought the sixth edition (1906) of Darwin's, The Origin of Species, in En- glish. Receiving some private tutoring from Mr. Thorgiles, an unusual teacher who had become headmaster of the sec- onciary school ~ once attended, ~ was now able to expand on my previous introduction to the sciences, mathematics, and the history of the civilizations of the worIcI. Mr. Thorgiles, more than anyone else, was responsible for introducing me ~o me sc-len~lnc mernoct. A new grasp of foreign languages also opener! German and English literature to me. Therefore, although ~ clict not attend formal high school T ~ 1_ C_ ~ ~ ~ . ~ ~ A _ _ ~ ~ 7 1 At oL'aL'ly clan Belter training, going on my own, with a little guidance here and there. Life during those later teens was interesting and absorbing, as I managed a small dairy farm, pursued liberal stuclies of many kincis, anc! was church or- ganist ant! church school teacher on the side. . My original plan had been to go to the Royal Agricultural College in Copenhagen as a preparation for a farming pro- fession. From ~ 9 ~ 0, however, at the age of about nineteen, ~ was also a part-time teacher at the secondary school ~ had attended a few years earlier, teaching primarily science. This experience was absorbing, and ~ deciclec! to change plans and attend the university instead. Starting at Copenhagen Uni- versity in 1913 at the age of twenty-two, ~ majored in botany and minored in physics, chemistry, geology, geography, and zoology. In 1920, at the age of thirty, ~ received my master's degree in natural history and geography. During my student clays, ~ continue<] to teach in the school but gradually tapered off on farming. ~ commuted the 30 miles to Copenhagen certain (lays of the week for the mandatory laboratory courses and some lectures. Two years ~ 9 ~ 6 to ~ 9 ~ ~were

OCR for page 74
80 BIOGRAPHICAL MEMOIRS spent in military service during World War I. At that time, stationed only ~ miles from Copenhagen, I commuted by bicycle. The University of Copenhagen was a true university rather than a school. It ctid not have residence requirements ant! one more or less developed one's own plans for study in consultation with the professors. There were excellent op- portunities for discussions with professors and with other students. Chresten Raunkiaer was my major professor in bot- any, P. Boysen Jensen in plant physiology, and Wilhelm Jo- hannsen in plant physiology and genetics. I knew Eugenius Warming, who at that time was retiree! but still highly inter- ested in the young students. August Krogh was my professor of animal physiology. ~ started physics uncler Niels Bohr, fol- lowecl by H. M. Hansen, chemistry under Einar Biilmann and Chr. Winther, and geography under H. P. Steensby. Intellectually, it was a highly stimulating environment. We were a small group of graduate students in biology who met for discussions, developing foundations for new approaches to systematics and ecology, sparked by the young science of genetics. In 1917 Winge defended his cloctoral thesis on the significance of the numbers of chromosomes in plants, in which he proposed the polyploidy theory. When ~ had my first interview with Wilhelm ~ohannsen in 1913, ~ mentioned that, for my master's clegree, T wanted to choose a specialty in genetics, and that ~ was interested in combining the genetic with the ecological approach to the v A, study of systematics. Johannsen had no use for ecology and was rather amuser! at the suggestion. Genetics was still new at the time, ant! although Johannsen was one of its pioneers, nobody had ever before specializect in genetics. It was finally arranged that ~ shouIcl have a specialty both in systematics and genetics. At Raunkiaer's suggestion ~ chose the violaceae because they were supposed to contain many natural hybrids.

OCR for page 74
JENS CHRISTIAN CLAUSEN 81 Just at the time when Winge developed the polyploidy theories, ~ found that Viola tricolor had thirteen and ~ arvensis (a close relative) seventeen pairs of chromosomes not a polyploid situation. Moreover the two species hybridized at their points of contact in the wild, and the hybrids were mod- erately fertile. It so happened that spontaneous hybrid col- onies of these two species of violet were located a short dis- tance from the headquarters of the artillery company to which ~ was assigned, and T set up my microscope on the office desk of the company command. This was undoubtedly one of the queerest cannons in artillery history! After the war ~ toured Denmark studying the wild pop- ulations of these two Viola species. ~ found prostrate, peren- nial races of Viola tricolor on exposed maritime sand dunes and annual, erect races inlandalthough often in close prox- imity to the maritime ones. Seedlings of the two kinds re- tained their identities even when grown remote from the coast. Viola arvensis was found to be associated with calcareous soils, tricolor with sandy soils. On neutral to faintly acid soils in the contact zones could be found swarms of interspecific hybrids, having intermecliate, irregular chromosome num- bers. Such spontaneous hybrids of various generations seg- regated similarly to the artificial hybrids. ~ presented these findings in two papers published in 192 ~ and 1922 in Botanisk Tidssbrift. They constitute one of the early approaches to ex- perimental 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. Remarkably enough, Gote Turesson's first papers on eco- types appeared in 1922, and we discovered that, unknown to each other, we had been working on the same subject of races of species adjusted to ecologically distinct environments at

OCR for page 74
82 BIOGRAPHICAL MEMOIRS sister universities only 30 miles apart, though in different countries. From that time on, there was fairly close liaison between Copenhagen and Luncl across the souncl. At the Royal Agricu1ttura1t College, Copenhagen, 1921-1931 After my master's degree, ~ started preparing for my teacher's credentials, although T tract already taught for ten years. Three months later, however, in April 1921, the first genetics department in Denmark was established at the Royal Agricultural College. 0jvincl Winge became professor, and ~ was offered the assistantship (corresponding to the rank of assistant professor). As a result ~ did not complete my teach- er's creclentials but lanclect unexpectedly at the college ~ orig- inally had aimed for. The field of the new department was to be basic research in genetics and not plant breeding a far-sighted arrange- ment 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 in- ducec! cancers of sugar beets ant! mice had abnormal chro- mosome numbers. We also studied interspecific hybric! prog- enies of several groups of plants of the genera Melandrium, Geum, Tragopogon, Erophila, and Hypericum. The papers relat- ing these results are in Winge's name and much has never been published, but it was an excellent experience to work with so many different kinds of organisms. On my own time, during evenings and vacations, ~ con- tinued the investigations of the violet species of the Melanium section. These experiments resulted in a series of papers that were publishect in Hereditas between 1923 and 193 I, and two papers on chromosome numbers anct relationships of species published in Annals of Botany between 1927 and 1929. Mrs.

OCR for page 74
JENS CHRISTIAN CLAUSEN 83 CIausen, although herself not a trained biologist, was a clect- icatec! and skillful helper in the clelicate anct time-consuming work of crossing, pollinating, and classifying the large F2 progenies, and of fixing and embeclding the buds for cyto- logical investigations. My doctoral thesis, "Genetical ant! Cytological Investiga- tions on Viola tricolor L. and ~ arvensis Murr.," was published in Hereditas in 1926. As far as ~ know, this is the first clem- onstration of the fact that taxonomic characters clistinguish- ing species are controlled by genes that can be analyzed. In Denmark, as in other Scandinavian countries, the cloctorate is based on advancecl research, the investigations are con- ductect after one has ceased being a student at the university, and there are no faculty advisors. The doctorate carries with it the right to lecture at the university on subjects of one's own choosing ant] to conduct courses there. In 1927, ~ was granted a Rockefeller fellowship for one year at the University of California at Berkeley. In 1929, to- gether with E. B. Babcock, who became a lifelong, close friend, ~ published a paper on chromosome pairing in three interspecific hybrids of Crepas. But the highly varied and di- versified California vegetation, which ~ saw in the company of Babcock anct others, tract an even greater impact on my ecological thinking. In ~ 93 I, after my return to Copenhagen, ~ published a paper on chromosome pairing in C. H. Osten- field's interspecific Polemonium hybrids. With the Carnegie Institution of Washington at Stanforcl, 1931 H. M. Hall pioneered! the transplant investigations in the Sierra Nevada beginning about 1921, and in 1923 cooper- ated with Babcock on a combiner! genetic-taxonomic inves- tigation on the hayfielcl tarweecls, the Euhemizonia section of the genus Hemizonia of the Madiinae. Hall wrote me aIreacly in 1922 after my first two papers had been published that he

OCR for page 74
84 BIOGRAPHICAL MEMOIRS was interested in conducting similar studies in California on plant relationships. We followed each other's work during the years ant! met both in California in 1927, ant! in Denmark in 1928. In 1930 ~ was unexpectedly offered a position as cy- tologist (later biologist) in his new program on experimental taxonomy, after the department of plant biology of the Car- negie Institution was established at Stanford in actdition to the earlier stations in the Sierra Nevada. ~ accepted this offer in 1931 ant! arrived at Stanford in late October. Tragically, Hall cliecl four months later in Washington, D.C. a great loss. ~ fount! myself unexpectedly chosen to take his place. It was fortunate for the future program that David D. Keck and William M. Hiesey, who had assisted Hall and knew the background of the plants were able to remain as part of the staff. Now began an interesting time of coop- eration between men of quite different backgrounds and leanings, representing cytogenetics, ecology, taxonomy, and physiology. Ecotype and Varied Environment Studies Hall's transplant investigations, using plants of many gen- era and families that were cloned and grown in highly con- trasting environments had been started to check on claims by Gaston Bonnier ant! F. E. Clements that lowland plants changed into alpines upon being transplanted, and vice versa. In analyzing the results of experiments under careful and constant control (publishecl in 1940), it became obvious that no such change takes place, although the transplanted ramets are mollified in their new environment. It was more significant, however, that species widely dis- tributect in western North America contain a fairly large number of physiologically distinct ecotypes, more so than Turesson observed in his extensive investigations in northern Europe. The most intensive sampling of natural populations

OCR for page 74
JENS CHRISTIAN CLAUSEN CHRONOLOGY 97 1891 Born March 11 in Eskilstrup, Denmark, 30 miles from Copenhagen, to Christen Agustinus Clausen and Christine Christensen 1905 - 1915 Farmer 1913 Entered Copenhagen University 1910-1916 Teacher in Danish secondary schools 1916 -1918 Artillery Corps, Danish Army 1918-1920 Teacher in Danish secondary schools 1921 Married Anna Hansen (died Palo Alto, California, August 24, 1956) 1921 - 1931 Research Assistant, Department of Genetics, Royal Agricultural and Veterinary College, Copenhagen 1926 Ph.D., Copenhagen University 1927 - 1928 Research Fellow, International Education Board at the University of California, Berkeley 1931 - 1956 Staff, Department of Plant Biology, Carnegie Insti- tution of Washington, Stanford, California 1936 Lecturer, University of Copenhagen 1943 Naturalized U.S. 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

OCR for page 74
98 BIOGRAPHICAL MEMOIRS SELECTED BIBLIOGRAPHY 1921 Studies on the collective species Viola tricolor L. Preliminary notes. Bot. Tidsskr., 37:205 - 21. 1922 Studies on the collective species Viola tricolor L. II. Bot. Tidsskr., 37:363-416. 1923 The variation of the wild pansy. Nat. Verden (Copenhagen), 218- 36. 1924 Increase of chromosome numbers in Viola experimentally induced by crossing. Hereditas, 5:29-32. 1926 Genetical and Cytological Investigations on Viola tricolor L. and ~ ar- vens~s Murr. Dissertation, University of Copenhagen, III-IV: 1-156. (Also in: Hereditas, 8: 1-156.) 1927 Non-Mendelian inheritance in Viola. Hereditas, 9:245-56. Chromosome number and the relationship of species in the genus Viola. Ann. Bot. (London), 41:677-714. The origin of cultivated pansies. Dan. Garden J., 3:17-18, 40-41. The chromosomes as carriers of the hereditary units. Frem, 777- 85. Has there been an evolution? Frem, 202-208. How do natural variations originate? Frem, 266-74. 1928 Evolution by hybridization between species. Frem, 332-36, 459- 63.

OCR for page 74
JENS CHRISTIAN CLAUSEN 1929 99 Chromosome number and relationship of some North American species of Viola. Ann. Bot., 43:741-64. Report of the Eighteenth Scandinavian Naturalist Congress, Copen- hagen: Exchange between chromatics of homologous chro- mosomes, pp. 239-45; discussion, pp. 245-46. 1930 Inheritance of variegation and of black flower color in Viola tricolor L. Hereditas, 13 :342-56. Male sterility in Viola orphanidis. Hereditas, 14:53-72. Induction of mutations by radiation, x-ray and radium (I and III). Nat. Verden (Copenhagen), 240-66, 289-312. 1931 Genetic studies in Polemonium. III. Preliminary account on the cy- tology of species and specific hybrids. Hereditas, 15:62-66. Danmarks Viol-Arter. Bot. Tidsskr., 41:317-35. Viola canina L., a cytologically irregular species. Hereditas, 15:67- 88. Cytogenetic and taxonomic investigations on Melanium violets. Hereditas, 15:219-308. 1932 Remarks upon H. G. Bruun's paper on Viola canine L. Hereditas, 17:67-70. Inheritance and synthesis of Melanium violets. Proc. Sixth Int. Congr. Genet., 2:346-49. Principles for a joint attack on evolutionary problems. Proc. Sixth Int. Congr. Genet., 2:21-23. With David D. Keck and William M. Heusi. Experimental tax- onomy: Problems and objectives, methods, Madiinae, Zausch- neria, Penstemon, Potentilla, miscellaneous materials. Carnegie Inst. Washington Yearb., 31:201-5. 1933 Cytological evidence for the hybrid origin of Pentstemon neotericus Keck. Hereditas, 18:65 -76.

OCR for page 74
100 BIOGRAPHICAL MEMOIRS With David D. Keck and William M. Heusi. Experimental taxon- omy: Madiinae, Zauschneris, Potentilla, Penstemon and Viola. Transplant experiments. Carnegie Inst. Washington Yearb., 32: 192-96. 1934 With David D. Keck and William M. Heusi. Experimental taxon- omy: Madiinae, field and herbarium studies, garden observa- tions, cytology, genetic studies, transplant studies, Zauschneria. Carnegie Inst. Washington Yearb., 33:173-77. 1935 With David D. Keck and William M. Hiesey. Experimental taxon- omy: Transplant studies, herbarium studies, field studies, gar- den studies, miscellaneous investigations. Carnegie Inst. Wash- ington Yearb., 34:201-6. 1936 The basis for natural systematic units. 19. Nordiska Skandinaviska Naturforskarmotet i Helsingfors, 520-23. With David D. Keck and William M. Hiesey. Experimental taxon- omy: Principles and problems, the species problem, investiga- tions on Madiinae, transplant studies, other investigations. Car- negie Inst. Washington Yearb., 35:208-14. With David D. Keck and William M. Hiesey. Experimental taxon- omy: Regional differentiation into ecotypes and ecospecies, the reaction patterns of ecotypes, other investigations. Carnegie Inst. Washington Yearb., 34:218-21. 1937 With David D. Keck and William M. Hiesey. Experimental taxon- omy: Compilation of manuscript, evolutionary patterns of the Madiinae, Madiinae hybrids, transplant experiments (varied environment investigations), studies abroad, other investiga- tions. Carnegie Inst. Washington Yearb., 36:209-14. 1939 With D. D. Keck and W. M. Hiesey. The concept of species based on experiment. Am. l. Bot., 26: 103-6.

OCR for page 74
JENS CHRISTIAN CLAUSEN 101 With David D. Keck and William Hiesey. Experimental taxonomy: Cytological differentiation within species complexes, causes of discontinuity in nature, other investigations. Carnegie Inst. Washington Yearb., 38:123-27. 1940 With D. D. Keck and W. M. Hiesey. Experimental Studies on the Nature of Species. I. E#ect of Varied Environment on Western North American Plants. Carnegie Institution of Washington Publication no. 520. Washington, D.C. With David D. Keck and William M. Hiesey. Experimental taxon- omy: The organization of plant groups, Madiinae hybrids, pro- duction of amphiploids, field studies, cytological studies, selec- tion experiment, status of present knowledge. Carnegie Inst. Washington Yearb., 39: 158-63. 1941 With David D. Keck and William M. Hiesey. Experimental taxon- omy: Criteria for relationship, relationships in the genus Layia, a possible new species of Layia, synthesis of a pre-existing spe- cies of Madia, other investigations. Carnegie Inst. Washington Yearb., 40: 160-70. 1942 With W. M. Hiesey and D. D. Keck. Relations between climate and intra-specific variation in plants. Am. Nat., 76:5-22. With David D. Keck, William M. Hiesey, and E. V. Martin. Exper- imental taxonomy: Hereditary composition of climatic races, physiological studies, investigations of the Madiinae, studies at the transplant stations. Carnegie Inst. Washington Yearb., 41: 126-34. 1943 With David D. Keck and William M. Hiesey. Experimental taxon- omy: The biosystematic units, evolutionary sequences, success or failure of amphiploids, investigations on range and forage grasses, other studies, guest investigator. Carnegie Inst. Wash- ington Yearb., 42:91-100.

OCR for page 74
102 BIOGRAPHICAL MEMOIRS 1944 With David D. Keck and William M. Hiesey. Experimental taxon- omy: The depletion of the western range, breeding of range grasses, taxonomy and distribution of Poa, biological character- istics of Poa and breeding technique, cytology of Poa, hybridi- zation of Poa, physiology of climatic races of Achillea, other in- vestigations. Carnegie Inst. Washington Yearb., 43:69-81. 1945 With D. D. Keck and W. M. Hiesey. Experimental Studies on the Nature of Species. II. Plant Evolution Through Amphiploidy and Autoploidy, with Examples from the Madiinae. Carnegie Institution of Wash- ington Publication no. 564. Washington, D.C. With David D. Keck and William M. Hiesey. Experimental taxon- omy: Breeding stock, Poa hybrids, transplant experiments, cy- tology of range grasses, Achillea studies, future investigations, guest investigators. Carnegie Inst. Washington Yearb., 44:71- 83. 1946 With David D. Keck and William M. Hiesey. Experimental taxon- omy: Climatic races of Achillea, Poa investigations, transplant stations. Carnegie Inst. Washington Yearb., 45 :111-20. 1947 With D. D. Keck and W. M. Hiesey. Heredity of geographically and ecologically isolated races. Am. Nat., 81 :1 14-33. With D. D. Keck and W. M. Hiesey. Plant relationship as deter- mined by experiment. In: Exhibitions Representing Results of Re- search Scholars, pp. 18-23. Washington, D.C.: Carnegie Institu- tion of Washington. With David D. Keck and William M. Hiesey. Experimental taxon- omy: The physiologic and genetic bases of climatic races; new hybrid poas for different environments; responses of the Poa hybrids to different climates; partial apomyxis: an evolutionary labyrinth; use of the station facilities. Carnegie Inst. Washing- ton Yearb., 46:95-104.

OCR for page 74
JENS C HRI STIAN C LAUSEN 1948 103 With D. D. Keck and W. M. Hiesey. Experimental Studies on the Nature of Species. III. Environmental Responses of Climatic Races of Achillea. Carnegie Institution of Washington Publication no. 581. Wash- ington, D.C. With David D. Keck and William M. Hiesey. Experimental taxon- omy: The range-grass program, climatic races of Potentilla glan- dulosa, genetic analysis of the climatic races, selection experi- ment, exploratory crossings. Carnegie Inst. Washington Yearb., 47: 105-10. 1949 Genetics of climatic races of Potentilla glandulosa. (Presented at the Eighth International Congress of Genetics.) Hereditas, Suppl. vol.: 162-72. Evolution in Crepes. Evolution, 3: 185-88. With David D. Keck, William M. Hiesey, and Paul Grun. Experi- mental taxonomy: Personnel and guest investigators, Potentilla gland?llosa, Poa investigations, California plant communities. Carnegie Inst. Washington Yearb., 48 :95-103. 1950 Leonas Lancelot Burlingame. Rec. Genet. Soc. Am., 19:27-29. With David D. Keck, William M. Hiesey, and Paul Grun. Experi- mental taxonomy: Growth of contrasting climatic races un- der varied temperatures, Poa investigations, Achillea hybrids, Mimulus studies, cytotaxonomy of the sagebrush, Dodecatheon, Phaseolus, Armenia. Carnegie Inst. Washington Yearb., 49: 101-1 1. 1951 Stages in the Evolution of Plant Species. Ithaca: Cornell Univ. Press. Reprinted: New York: Hafner Press (1962~. With William M. Hiesey, David D. Keck, Paul Grun, Axel Nygren, and Malcolm Nobs. Climatic tolerances of Poa species and hy- brids. Carnegie Inst. Washington Yearb., 50:105-8. With Paul Grun, Axel Nygren, and Malcolm Nobs. Genetics and evolution of Poa. Carnegie Inst. Washington Yearb., 50:109-11.

OCR for page 74
04 BIOGRAPHICAL MEMOIRS With William M. Hiesey and Malcolm Nobs. Genetics of climatic races and species in Achillea. Carnegie Inst. Washington Yearb., 50:115-17. 1952 With William M. Hiesey, Paul Grun, and Malcolm A. Nobs. Exper- imental taxonomy: Survey of the range grass program, new Poa hybrids. Carnegie Inst. Washington Yearb., 51:107-17. 1953 With William M. Hiesey and Malcolm A. Nobs. Experimental tax- onomy: The Poa program. Carnegie Inst. Washington Yearb., 52: 169-73. With William M. Hiesey and Malcolm A. Nobs. Genetic studies on ecological races. Carnegie Inst. Washington Yearb., 52:174-76. 1954 Partial apomixis as an equilibrium system in evolution. (Presented at the Ninth International Congress of Genetics, Bellagio, Italy, 1952.) Caryologia (Suppl. vol.), 6:469-79. The ecological race as a variable biotype compound in dynamic balance with its environment. In: Proceedings, Symposium on Ge- netics of Population Structure, pp. 104-13. International Union of Biological Sciences Series B. no. 15. Secretariat-General de ['Union Internationale des Sciences Bioligiques. With William M. Hiesey and Malcolm A. Nobs. Experimental tax- onomy: The Poa program. Carnegie Inst. Washington Yearb., 53: 150-56. With Edward L. Triplett. Chromosome numbers of hybrid Poa lines. Carnegie Inst. Washington Yearb., 53:156-57. Evolutionary differentiation at tropical latitudes. Carnegie Inst. Washington Yearb., 53: 162-64. 1955 With William M. Hiesey and Malcolm A. Nobs. Experimental tax- onomy: Poa investigations. Carnegie Inst. Washington Yearb., 54: 170-175. Diploid, tetrapoloid and hexaploid hybrids of Achillea, Chromosome 182-183.

OCR for page 74
JENS CHRISTIAN CLAUSEN 105 With Lois M. Cox. Numabers of hybrid Poa lines. Carnegie Insti- tute Washington Yearb., 54: 175-77. 1956 With William M. Hiesey and Malcolm A. Nobs. Experimental tax- onomy: Studies in Poa, plantings of Achillea and Mimulus. Car- negie Inst. Washington Yearb., 55:236-39. 1957 With William M. Hiesey and Malcolm A. Nobs. Contrasting toler- ance ranges of apomictic species and hybrids of Poa. Carnegie Inst. Washington Yearb., 56:293-95. 1958 With W. M. Hiesey. Phenotypic expression of genotypes in con- trasting environments. In: Scottish Plant Breeding Station Report, pp. 41-51. The function and evolution of ecotypes, ecospecies, and other nat- ural entities. Uppsala Univ. Arsskr., 6:139-43. Also in: System- atics of Today, Uppsala, Lundequistska Bokhandeln. With William M. Hiesey and Malcolm A. Nobs. Poa investigations. Carnegie Inst. Washington Yearb., 57:272-78. With W. M. Hiesey. Experimental Studies on the Nature of Species. IV Genetic Structure of Ecological Races. Carnegie Institution of Washington Publication no. 615. Washington, D.C. 1959 Gene systems regulating characters of ecological races and subspe- cies. In: Proceedings of the Tenth International Congress of Genetics, vol. 1, pp. 434-43. With William M. Hiesey and Malcolm A. Nobs. Evolutionary pro- cesses in apomictic species of Poa. Carnegie Inst. Washington Yearb., 58:358-60. 1960 A simple method for sampling of natural populations. In: Scottish Plant Breeding Station Report, pp. 69-75. With W. M. Hiesey. The balance between coherence and variation in evolution. Proc. Natl. Acad. Sci. USA, 46:494-506.

OCR for page 74
106 BIOGRAPHICAL MEMOIRS With Malcolm A. Nobs and William M. Hiesey. Interlatitudinal se- lection experiments in Poa. Carnegie Inst. Washington Yearb., 59:322-24. 1961 Introgression facilitated by apomixis in polyploid Poa. Euphytica, 10:87-94. With P. I. Watson. Phenotypic responses to contrasting environ- ments in the genus Poa. In: Scottish Plant Breeding Station Report, pp. 64-78. With Malcolm A. Nobs and William M. Hiesey. Studies in Poa. Car- negie Inst. Washington Yearb., 60:384. 1962 With Malcolm A. Nobs, William M. Hiesey, and Frank Nicholson. Transplant station activities. Carnegie Inst. Washington Yearb., 61:312-13. With William M. Hiesey and Malcolm A. Nobs. Studies in Poa hy- bridization. Carnegie Inst. Washington Yearb., 61 :325-33. With R. B. Channell. The North American field pansy, Viola rafin- esauii. Carnegie Inst. Washington Yearb., 61:333-34. 1963 Tree line and germ plasm- a study in evolutionary limitations. Proc. Natl. Acad. Sci. USA, 50:860-68. Studies on the distribution of tree species. Carnegie Inst. Washing- ton Yearb., 62:394-98. Cytotaxonomy and distributional ecology of western North Amer- ican violets. Carnegie Inst. Washington Yearb., 62:398-99. 1964 With R. B. Channell and Uzi Nur. Viola rafinesquii, the only Melan- ium violet native to North America. Rhodora, 66:32-46. Cytotaxonomy and distributional ecology of western North Amer- ican violets. Madrono, 17: 173-97. New combinations in western North American violets. Madrono, 17:295. Synthesis. In: Genetics Today: Proceedings of the Eleventh International Congress of Genetics, vol. 2, pp. 447-49.

OCR for page 74
JENS CHRISTIAN CLAUSEN 107 1965 Prof. 0jvind Winge. 19. Maj 1886-5. April 1964. Saertryk af Na- turhistorisk Tidende, 28-29:60-66. Population studies of alpine and subalpine races of conifers and willows in the California High Sierra Nevada. Evolution, 19:56-68. Microclimatic and vegetational contrasts within a sub-alpine valley. Proc. Natl. Acad. Sci. USA, 53: 1315 -19. Vegetational and climatic contrasts within the Harvey Monroe Hall natural area. Carnegie Inst. Washington Yearb., 64:431-35. 1966 Stability of genetic characters in Tragopogon species through 200 years. Trans. Proc. Bot. Soc. Edinburgh, 40:148-58 . . . . i, Stored Developments In the cytogenet~cs ot lragopon. Carnegie Inst. Washington Yearb., 65:471-73. 1967 Biosystematic consequences of ecotypic and chromosomal differ- entiation. Taxon, 16:271-79. Clusters of tree species on both sides of the Pacific. Carnegie Inst. Washington Yearb., 66:234-42. 1969 Vegetation of the Harvey Monroe Hall natural area. Carnegie Inst. Washington Yearb., 68 :643-44. 1970 Genecology and breeding. In: Estratto da Eurarpia, Fifth Congress of the European Association for Research on Plant Breeding, Milan, 1968, pp. 405-24. The Harvey Monroe Hall Natural Area. Carnegie Institution of Wash- ington D.P.B. Publication no. 459. Washington, D.C.