What do biologists think of Lynn Margulis

Labor Journal 2018-06

6/2018 | 71 BOOK ET AL. The fact that the original edition of Symbiotic Planet has made it onto the market as a German translation after twenty years shows that the subject of evolution is still brand new. The author and former professor of biology at the University of Massachusetts, Lynn Margulis, describes her view of evolution here. Her deep-rooted interest in biology and the development of life can be felt throughout the book. It makes it clear that symbiosis is a fundamental principle that was necessary in order to make the majority of the life we ​​know today possible. The entire world of plants and animals as well as the world of fungi and protists can be traced back to symbiotic relationships: Former prokaryotes now eke out their existence as cell organelles. But it goes one step further: Margulis is convinced that symbiosis is the fundamental principle in the creation of new species. Contrary to the doctrinal opinion, she considers reports that the emergence of a new species can be shown in the laboratory as an indication. One team succeeded, for example, in generating a Drosophila population through constant temperature increases and selection, which could no longer produce any offspring with their “original” relatives. The reason for this, however, was a symbiotic bacterium that was lost in Drosophilas raised at higher temperatures. While this represented a substantiation of her thesis for Margulis, for other colleagues it was questionable whether it was possible to speak of a new species - precisely because the cause was a bacterium. But what is true of the dogma that when a new species emerges, only its own DNA is relevant and not that of existing symbionts? LynnMargulis repeats the message several times in the course of the book not to think in dogmas. At all times there are theories that are treated as “truth”; thoughts and theories that deviate from them are all too quickly ridiculed. She is well aware that her approach to creating new species is a form of Lamarckism. Because symbiogenesis does not necessarily change one's “own” DNA; rather, additional features are acquired - in fact, even with additional genetic material. The first half of “The Symbiotic Planet” is actually very exciting. Margulis’s thought processes are logical, easy to understand and she refuses to follow common theses if they do not make sense for them. This ultimately led to their development of the serial endosymbiont theory. Of the four underlying postulates - highly controversial at the time, because bacteria were mainly known as pathogenic germs - at least three are now considered to be confirmed and recognized: Our cells emerged from archaea, mitochondria are descended from so-called purple bacteria and chloroplasts have freely living photosynthetically active cyanobacteria as ancestors. It remains to be seen whether the fourth thesis - the amalgamation of archaea with spirochetes, which is said to have taken place first - can be confirmed at some point. In the second half of the book, Lynn Margulis takes up other topics. It discusses the problems that have arisen in the taxonomic classifications of living things and that will arise again and again. She goes back to the origin of life and wonders how it could have come about. And it looks at sex and meiosis in terms of evolution. The individual chapters seem more like additions and make the second half of the book appear somewhat more inhomogeneous. It also shows how diverse the symbiotic relationships around us look. Different, small ecosystems in which living things interact with each other and are dependent on each other. Partly of great, but underestimated importance - such as the community between fungus and plant in mycorrhiza. As a result of the many symbiotic relationships, Lynn Margulis ultimately understands evolution as a symbiotic concept. In the last chapter, Margulis summarizes the importance of this concept and the interaction of the many small ecosystems. To do this, she uses the Gaia hypothesis. The name Gaia comes from Greek mythology and denotes the mother of all gods, the “Great Earth Mother”. The choice of this term quickly results in the risk of being accused of being “non-scientific” or of misinterpretation. But Gaia is not to be seen as a single living being or a person. Gaia is one huge ecosystem that arises from the sum of many smaller ecosystems. Or, to put it in the words of Greg Hinkel, a former student of Lynn Margulis: “Gaia is a symbiosis seen from space.” Overall, a worthwhile book, full of observation and acumen from the author. The insights into their private and academic life make the reader feel like they are on their own little voyage of discovery. “The Symbiotic Planet” makes you want to deal more with symbiotic relationships and, above all, with the microorganisms involved, and motivates you to approach questions openly and to question existing dogmas from time to time. Darja Henseler A journey of discovery through the symbiotic planet - with the conclusion that dogmas are for the cat. Lynn Margulis The symbiotic planet or: How evolution really went Westend Verlag (2018) Language: German, 208 pages Price: 20 euros (hardcover) 15.99 euros (eBook) The basic principle of species development

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