Léon Croizat

Léon Camille Marius Croizat (* July 16, 1894 in Turin, † November 10, 1982 in Coro ) was a French-Italian botanist who worked in Venezuela and developed the Panbiogeographie as a hypothesis that the evolution of organisms over large areas and long periods of time to explain. Its official botanical author abbreviation is " Croizat ".

Life

Léon Croizat was born to French parents in Turin. There he studied law as a day job, without ever denying his tendency to natural history. So he devoted himself after his graduation in botany and zoology. He developed ideas that brought him against the Darwinism of his time to hypotheses about the evolution of life on the Earth's surface over long periods. During the First World War he served from 1914 to 1919 in the Italian army. In 1923 he emigrated with his wife and two children to New York. To earn next day laborers work nor money, he painted watercolors which were exhibited at the Brooklyn Museum of Art. After the stock market crash of 1929/1930, the art market collapsed, however, and Croizat moved to Paris, where he remained with his family until 1936. Between 1936 and 1946 he lived in the U.S., where he worked as a research assistant to Elmer Drew Merrill ( 1876-1956 ) at the Arnold Arboretum of Harvard University. Since he French, Italian, Spanish, Portuguese, Latin, Russian, German, and with the help of a dictionary spoke Greek, he could be incorporated immediately in the herbarium at the intricacies of the Euphorbiaceae.

Croizat in 1947 by the Swiss botanist Henri Pittier ( 1857-1950 ) invited to Venezuela. He accepted a position in the Faculty of Agriculture, University of Venezuela. In 1951 he was appointed professor of botany and ecology at the Universidad de Los Andes, Venezuela, appointed.

From 1951 to 1952 he took part as a botanist at the French- Venezuelan expedition led by José Maria Cruxent that examined the sources of the Orinoco in the footsteps of Alexander von Humboldt. He divorced at this time of his first wife to marry Catalina, an immigrant from Hungary child psychologist can. Catalina gave him after completing her second degree as a landscape architect the financial freedom to be able to 1953 up all official academic offices and to devote himself exclusively to interest him biological problems.

In the years 1959/1960 he undertook an expedition through South America, 1962/1963 he visited Europe, where he gave lectures in Paris at the Linnean Society in London and the Muséum national d' histoire naturelle. He lived with his wife until 1975 in Caracas. Then he took her along the line of " Jardin Botanico Xerofito " in Coro, a city about 400 kilometers west of Caracas. There, the two had begun in 1970 with the investment and development of a botanical garden. The garden was named after his death in his honor " Jardin Xerofito Dr. Leon Croizat ". Until her death in 1997, Catalina Croizat remained director.

Léon Croizat died on November 30, 1982 in Coro of a heart attack. Seven books and about 300 scientific articles, together about 15,000 printed pages, he was able to publish during his lifetime.

Honors

Croizat received from the Venezuelan State to Henri Pittier Merit for nature conservation. The Italian government honored him with its Order of Merit. Plant and animal species in South America were named in his honor.

Panbiogeographie

Developed by Léon Croizat method of Panbiogeographie based on a cartographic method in which the current distribution of a taxon or several taxa is entered on a world map and disjunctions occurring, so interruptions in a distribution area, drive around with lines. After Croizats hypothesis predicts the pattern thus created the potential or former area of ​​distribution of a taxon dar.

To explain interruptions in the currently visible area of ​​distribution, postulated Croizat that common ancestor of taxa would have been used in earlier geological periods on. Extinction events in later periods then led to a patchy distribution area. Croizat looked at the evolution of organisms essentially as determined by time, space and form. Of these three factors, the space is the one where the biogeography of the most accepting.

Scientific recognition

Croizats hypotheses are controversial to this day. While scientists who ascribe to the active or passive dissemination of a taxon this in recent times a major role Croizats approach reject hold, other him. One of the most original thinkers of the modern comparative biology He laid the foundation for an interdisciplinary examination of organismic distribution patterns between biology and geography.

Writings (selection )

• Manual of phytogeography, or An Account of Plant Dispersal Throughout the World. Junk, The Hague 1952.
• Panbiogeography or An Introductory Synthesis of zoogeography, phytogeography, Geology; with notes on evolution, systematics, ecology, anthropology, etc. Caracas in 1958.
• Principia Botanica or Beginnings of Botany. Caracas in 1961.
• Space, Time, Form: The Biological Synthesis. Caracas in 1964.
• Vicariance / vicariism, panbiogeography, " vicariance Biogeography, " etc.: a clarification. In: Systematic Zoology. Volume 31, 1982, p 291-304.