Endosymbiotic Theory
Description
From the bio of Lynn Margulis in Brittanica:
"Throughout most of her career, Margulis was considered a radical by peers who pursued traditional Darwinian “survival of the fittest” approaches to biology. Her ideas, which focused on symbiosis—a living arrangement of two different organisms in an association that can be either beneficial or unfavourable—were frequently greeted with skepticism and even hostility. Among her most important work was the development of the serial endosymbiotic theory (SET) of the origin of cells, which posits that eukaryotic cells (cells with nuclei) evolved from the symbiotic merger of nonnucleated bacteria that had previously existed independently. In this theory, mitochondria and chloroplasts, two major organelles of eukaryotic cells, are descendants of once free-living bacterial species. She explained the concept in her first book, Origin of Eukaryotic Cells (1970). At the time, her theory was regarded as far-fetched, but it has since been widely accepted."
(https://www.britannica.com/biography/Lynn-Margulis)
Publications
Symbiosis in Cell Evolution
"She elaborated in her 1981 classic, Symbiosis in Cell Evolution, proposing that another symbiotic merger of cells with bacteria—this time spirochetes, a type of bacterium that undulates rapidly—developed into the internal transportation system of the nucleated cell. Margulis further postulated that eukaryotic cilia were also originally spirochetes and that cytoplasm evolved from a symbiotic relationship between eubacteria and archaebacteria (see archaea)."
Five Kingdoms
"Her 1982 book Five Kingdoms, written with American biologist Karlene V. Schwartz, articulates a five-kingdom system of classifying life on Earth—animals, plants, bacteria (prokaryotes), fungi, and protoctists. The protist kingdom, which comprises most unicellular organisms (and multicellular algae) in other systems, is rejected as too general."
(https://www.britannica.com/biography/Lynn-Margulis)
Symbiotic Planet
* Book: Symbiotic Planet: A New Look At Evolution. by Lynn Margulis. Basic Books, 1999
"Although Charles Darwin’s theory of evolution laid the foundations of modern biology, it did not tell the whole story. Most remarkably, The Origin of Species said very little about, of all things, the origins of species. Darwin and his modern successors have shown very convincingly how inherited variations are naturally selected, but they leave unanswered how variant organisms come to be in the first place. In Symbiotic Planet, renowned scientist Lynn Margulis shows that symbiosis, which simply means members of different species living in physical contact with each other, is crucial to the origins of evolutionary novelty. Ranging from bacteria, the smallest kinds of life, to the largest — the living Earth itself — Margulis explains the symbiotic origins of many of evolution’s most important innovations. The very cells we’re made of started as symbiotic unions of different kinds of bacteria. Sex — and its inevitable corollary, death — arose when failed attempts at cannibalism resulted in seasonally repeated mergers of some of our tiniest ancestors. Dry land became forested only after symbioses of algae and fungi evolved into plants. Since all living things are bathed by the same waters and atmosphere, all the inhabitants of Earth belong to a symbiotic union. Gaia, the finely tuned largest ecosystem of the Earth’s surface, is just symbiosis as seen from space. Along the way, Margulis describes her initiation into the world of science and the early steps in the present revolution in evolutionary biology; the importance of species classification for how we think about the living world; and the way “academic apartheid” can block scientific advancement."
(https://www.basicbooks.com/titles/lynn-margulis/symbiotic-planet/9780465072729/)
More information
Bio of Lynn Margulis
From the Wikipedia:
"Lynn Margulis (born Lynn Petra Alexander; March 5, 1938 – November 22, 2011) was an American evolutionary theorist, biologist, science author, educator, and science popularizer, and was the primary modern proponent for the significance of symbiosis in evolution. Historian Jan Sapp has said that "Lynn Margulis's name is as synonymous with symbiosis as Charles Darwin's is with evolution." In particular, Margulis transformed and fundamentally framed current understanding of the evolution of cells with nuclei – an event Ernst Mayr called "perhaps the most important and dramatic event in the history of life" – by proposing it to have been the result of symbiotic mergers of bacteria. Margulis was also the co-developer of the Gaia hypothesis with the British chemist James Lovelock, proposing that the Earth functions as a single self-regulating system, and was the principal defender and promulgator of the five kingdom classification of Robert Whittaker."