The King of Observers

Fritz Müller (Johann Friedrich Theodor Fritz Müller), was a German naturalist. He was born near Erfurt in 1821. He was the son of a minister, and he began studying pharmacy but he quickly abandoned in order to turn to study mathematics and natural sciences. He obtained his doctor’s diploma in 1844, with a thesis on leeches. Then he decided to study medicine in 1845, because of his dream to leave Germany in order to discover tropical countries. Indeed he was very interested about the wildlife in these countries. But this liberal considered that the laws of nature and Christian mystic were irreconcilable, and as a consequence he decided to renounce his religion to become an atheist. But his opinion prevented him from exercising his doctor’s job and he had to close his office.^[1]&[2]

Because of his dream, he decided to emigrate to Blumenau with his wife, his daughter and his brother in 1852. Blumenau was a German city established in the southeast of Brazil, on the river Itajai-Açu, halfway between Rio de Janeiro and the Uruguayan border. There he became a professor of natural history. He taught mathematics in Desterro, a coastal city, before the Jesuits took the control of the college. They obliged him to leave the college because of his position regarding religion. He obtained a position of itinerant naturalist for the Natural history museum of Rio, in 1876. Nevertheless he had to leave it in 1891, refusing to settle down in Rio. He lived his last years in Blumenau, where he was struck by the deaths of his wife and his daughter, then by the suicide of his sister who was in Berlin. He died in Blumenau on May 21st, 1897; he was 76 years old.^[1]&[2]

During all his life he was passionate about flora and fauna. He studied them a lot during his stay in Desterro then when he was a naturalist. He was notably interested in shellfish, jellyfishes, fertilization of flowers, orchids and in bees… Although he lived at the end of the world, he could read Charles Darwin’s work, On the origin of species, and he became a convinced defender of the thesis of the natural selection. In 1864, he wrote his single work, Für Darwin (For Darwin)^[3] to defend his thesis thanks to its own observations, in particular on shellfish and crawfishes,^[1]&[2] He proposed the hypothesis that the successive developmental phases of an embryo remind the successive stages of the evolution of an organism. This «law» would be excessively taken up and systematized by Ernst Haeckel to explain the passing organs of an embryo. He was used to write many letters with numerous scientists and naturalists of this age, for example with Heinrich Müller, his brother, Charles Darwin and Ernst Haeckel, to discuss about evolution and natural sciences.^[1]

He took a place in the History of biology, by giving his name to a type of mimicry: the müllerien mimicry. Some species, in particular butterflies, have acquired a toxicity to fight their predators by a behavioral adaptation. The young predators taste some of the representatives of the concerned species of butterflies, they notice their bad taste and learn to eliminate them from their diet. However it involves that the butterfly species sacrifices some individuals to the education of its predators. Therefore two toxic species may find an “advantage” by miming each other to reduce the number of individuals sacrificed among each species. The insects, which are not programmed genetically to look like the toxic individuals of the other species, have more risks of being devoured by the predators because they will not have been recognized themselves as toxic. These individuals thus have a weaker fitness, because they have a greater risk to be eaten.^[4]&[5] Fritz Müller is the first one to have put a mathematic basis to describe this model of mimicry. The genetic basis of this mimicry was recently discovered by studying the butterfly model Heliconius Numata : it is the result of the works of a scientists’ team of the Natural History Museum of Paris and of the NATIONAL CENTER FOR SCIENTIFIC RESEARCH (CNRS).^[6]&[7]

But this mechanism has a parallel in the plant kingdom! Some plants from different species display similar flowers in order to attract the same pollinators. Following the example of the animal case where both butterflies are toxic, both plants reward pollinators, as a consequence there is not duplicity. It is the case of several flowers pollinated by hummingbirds, such as Ipomopsis aggregata which includes several subspecies which look very similar.^[8] This phenomenon was also looked for different species, as Lantana and Asclepias, which produce both plentiful of nectar and seem to be mülleriens imitators one of the other one.

Fritz Müller, described by Darwin as «the king of observers» for his talents of naturalist and draftsman, left his mark in the history of botany: F.J. Müll. is his official botanical abbreviation, associated with numerous plants that he discovered and described.^[1]

Illustrations :

Photo 1 : Fritz Müller

Photo 2 : Foto de Cortesia de Luiz Roberto Fontes. Reprodução do livro Für Darwin (“Para Darwin”) http://viajeaqui.abril.com.br/materias/a-prova-da-evolucao#2

Photo 3 : Misahuallí – Numata Longwing Butterfly. Photo by Drriss. [cc]by-nc-sa[/cc]

Photo 4 : Foto de Djan Chu. Ilustração reproduzida do livro Fritz Müller – Werke, Briefe und Leben, de Alfred Möller, Museu de Zoologia da Universidade de São Paulo http://viajeaqui.abril.com.br/materias/a-prova-da-evolucao#1

Photo 5 : Ipomopsis aggregata. Photo by BMC Ecology. [cc]by-sa[/cc]

Photo 5 : Hummingbird and Lantana. Photo by odonata98/. [cc]by-nd[/cc]

Photo 7 : Hummingbird on common milkweed. Photo by The Natural Capital. [cc]by-nc-sa[/cc]

Bibliography :

1. [1] Wikipedia, Fritz Müller (1821-1897), http://fr.wikipedia.org/wiki/Fritz_M%C3%BCller_%281821-1897%29
2. [2] Encyclopédie Larousse, Fritz Müller, http://www.larousse.fr/encyclopedie/personnage/M%C3%BCller/134347
3. [3] F. Müller, Pour Darwin, 1864, http://archive.org/details/frdarwin00mlgoog
4. [4] Joron M., Olivieri I., La sélection naturelle,
   http://www.cnrs.fr/cw/dossiers/dosevol/decouv/articles/chap7/olivieri.html
5. [5] Wikipédia, Mimétisme, http://fr.wikipedia.org/wiki/Mim%C3%A9tisme
6. [6] Dias-Alves M., Le «supergène» du mimétisme déchiffré chez des papilons d’Amazonie, National Geographic France, 2011, http://www.nationalgeographic.fr/actualite/supergene-mimetisme-papillons/7910075/
7. [7] Counterman BA, F Araujo-Pérez, HM Hines, SW Baxter, CM Morrison, DP Lindstrom, R Papa, L Ferguson, M Joron, RH ffrench-Constant, C Smith, D Nielsen, R Chen, CD Jiggins, RD Reed, G Halder, J Mallet, and WO McMillan (2010), Genomic hotspots for adaptation: the population genetics of Müllerian mimicry in Heliconius erato. PLoS Genetics 6: e1000796, http://heliconius.zoo.cam.ac.uk/joron/counterman10plosgen.pdf
8. Brown J.H., Kodric-Brown A., Convergence, competition, and mimicry in a temperate community of hummingbird-pollinated flowers, Ecology, 60(5), 1979 pp. 1022-1035 http://www.jstor.org/discover/10.2307/1936870?uid=3738016&uid=2&uid=4&sid=21102250541967