Wilhelm Johannsen
Encyclopedia
Wilhelm Johannsen was a Danish
botanist, plant physiologist and geneticist
. He was born in Copenhagen. While very young, he was apprenticed to a pharmacist
and worked in Denmark
and Germany
beginning in 1872 until passing his pharmacist's exam in 1879. In 1881, he became assistant in the chemistry department at the Carlsberg Laboratory
under the chemist Johan Kjeldahl
. Johannsen studied the metabolism
of dormancy
and germination
in seed
s, tuber
s and bud
s. He showed that dormancy
could be broken by various anesthetic compounds, such as diethyl ether
and chloroform
.
In 1892, he was appointed lecturer at Royal Veterinary and Agricultural University
and later became professor of botany
and plant physiology
. He taught plant physiology. His most well-known research concerned so-called pure lines of the self-fertile common bean
. He was able to show that even in population
s homozygous for all traits, i.e. without genetic variation, seed size followed a normal distribution. This was attributable to resource provision to the mother plant and to the position of seeds in pods and of pods on the plant. This led him to coin the terms phenotype
and genotype
. His findings led him to oppose contemporary Darwinists
, most notably Francis Galton
and Karl Pearson
, who held the occurrence of normal distributed trait variation in population
s as proof of gradual genetic variation on which selection could act. Only with the modern evolutionary synthesis
, was it established that variation needed to be heritable to act as the raw material for selection
.
The terms phenotype
and genotype
were created by Wilhelm Johannsen and first used in his paper Om arvelighed i samfund og i rene linier and in his book Arvelighedslærens Elementer. This book was rewritten, enlarged and translated to German as Elemente der exakten Erblichkeitslehre. It was in this book Johannsen introduced the term gene
. This term was coined in opposition to the then common pangene that stemmed from Darwin's
theory of pangenesis
. The book became one of the founding texts of genetics.
Also in 1905, Johannsen was appointed professor of plant physiology
at the University of Copenhagen
, becoming vicechancelor in 1917. In December 1910, Johannsen was invited to give an address before the American Society of Naturalists
. This talk was printed in the American Naturalist
. In 1911, he was invited to give a series of four lectures at Columbia University
.
(elected 1915).
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...
botanist, plant physiologist and 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...
. He was born in Copenhagen. While very young, he was apprenticed to a pharmacist
Pharmacist
Pharmacists are allied health professionals who practice in pharmacy, the field of health sciences focusing on safe and effective medication use...
and worked in Denmark
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...
and Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
beginning in 1872 until passing his pharmacist's exam in 1879. In 1881, he became assistant in the chemistry department at the Carlsberg Laboratory
Carlsberg Laboratory
The Carlsberg Laboratory in Copenhagen, Denmark was created in 1875 by J. C. Jacobsen, the founder of the Carlsberg brewery, for the sake of advancing biochemical knowledge, especially relating to brewing. It featured a Department of Chemistry and a Department of Physiology...
under the chemist Johan Kjeldahl
Johan Kjeldahl
Johan Gustav Christoffer Thorsager Kjeldahl , was a Danish chemist who developed a method for determining the amount of nitrogen in certain organic compounds using a laboratory technique which was named the Kjeldahl method after him....
. Johannsen studied the metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
of dormancy
Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
and germination
Germination
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the...
in seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s, tuber
Tuber
Tubers are various types of modified plant structures that are enlarged to store nutrients. They are used by plants to survive the winter or dry months and provide energy and nutrients for regrowth during the next growing season and they are a means of asexual reproduction...
s and bud
Bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of the stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have...
s. He showed that dormancy
Dormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
could be broken by various anesthetic compounds, such as diethyl ether
Diethyl ether
Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...
and chloroform
Chloroform
Chloroform is an organic compound with formula CHCl3. It is one of the four chloromethanes. The colorless, sweet-smelling, dense liquid is a trihalomethane, and is considered somewhat hazardous...
.
In 1892, he was appointed lecturer at Royal Veterinary and Agricultural University
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...
and later became professor of 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...
and plant physiology
Plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...
. He taught plant physiology. His most well-known research concerned so-called pure lines of the self-fertile common bean
Common bean
Phaseolus vulgaris, the common bean, is an herbaceous annual plant domesticated independently in ancient Mesoamerica and the Andes, and now grown worldwide for its edible bean, popular both dry and as a green bean. The leaf is occasionally used as a leaf vegetable, and the straw is used for fodder...
. He was able to show that even in population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
s homozygous for all traits, i.e. without genetic variation, seed size followed a normal distribution. This was attributable to resource provision to the mother plant and to the position of seeds in pods and of pods on the plant. This led him to coin the terms phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
and genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
. His findings led him to oppose contemporary Darwinists
Darwinism
Darwinism is a set of movements and concepts related to ideas of transmutation of species or of evolution, including some ideas with no connection to the work of Charles Darwin....
, most notably Francis Galton
Francis Galton
Sir Francis Galton /ˈfrɑːnsɪs ˈgɔːltn̩/ FRS , cousin of Douglas Strutt Galton, half-cousin of Charles Darwin, was an English Victorian polymath: anthropologist, eugenicist, tropical explorer, geographer, inventor, meteorologist, proto-geneticist, psychometrician, and statistician...
and Karl Pearson
Karl Pearson
Karl Pearson FRS was an influential English mathematician who has been credited for establishing the disciplineof mathematical statistics....
, who held the occurrence of normal distributed trait variation in population
Population
A population is all the organisms that both belong to the same group or species and live in the same geographical area. The area that is used to define a sexual population is such that inter-breeding is possible between any pair within the area and more probable than cross-breeding with individuals...
s as proof of gradual genetic variation on which selection could act. Only with the modern evolutionary synthesis
Modern evolutionary synthesis
The modern evolutionary synthesis is a union of ideas from several biological specialties which provides a widely accepted account of evolution...
, was it established that variation needed to be heritable to act as the raw material for selection
Selection
In the context of evolution, certain traits or alleles of genes segregating within a population may be subject to selection. Under selection, individuals with advantageous or "adaptive" traits tend to be more successful than their peers reproductively—meaning they contribute more offspring to the...
.
The terms phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
and genotype
Genotype
The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific character under consideration...
were created by Wilhelm Johannsen and first used in his paper Om arvelighed i samfund og i rene linier and in his book Arvelighedslærens Elementer. This book was rewritten, enlarged and translated to German as Elemente der exakten Erblichkeitslehre. It was in this book Johannsen introduced the term gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
. This term was coined in opposition to the then common pangene that stemmed from Darwin's
Charles Darwin
Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...
theory of pangenesis
Pangenesis
Pangenesis was Charles Darwin's hypothetical mechanism for heredity. He presented this 'provisional hypothesis' in his 1868 work The Variation of Animals and Plants under Domestication and felt that it brought 'together a multitude of facts which are at present left disconnected by any efficient...
. The book became one of the founding texts of genetics.
Also in 1905, Johannsen was appointed professor of plant physiology
Plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...
at the University of Copenhagen
University 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...
, becoming vicechancelor in 1917. In December 1910, Johannsen was invited to give an address before the American Society of Naturalists
American Society of Naturalists
The American Society of Naturalists was founded in 1883 and is one of the oldest professional societies dedicated to the biological sciences in North America...
. This talk was printed in the American Naturalist
American Naturalist
The American Naturalist is a monthly peer-reviewed scientific journal that was established in 1867. It is published by the University of Chicago Press on behalf of the American Society of Naturalists. The journal covers research in ecology, evolutionary biology, population, and integrative biology....
. In 1911, he was invited to give a series of four lectures at Columbia University
Columbia University
Columbia University in the City of New York is a private, Ivy League university in Manhattan, New York City. Columbia is the oldest institution of higher learning in the state of New York, the fifth oldest in the United States, and one of the country's nine Colonial Colleges founded before the...
.
Miscellaneous
Corresponding member of the Academy of Natural Sciences of PhiladelphiaAcademy of Natural Sciences
The Academy of Natural Sciences of Drexel University, formerly Academy of Natural Sciences of Philadelphia, is the oldest natural science research institution and museum in the New World...
(elected 1915).