Acquiring Genomes: A Theory of the Origins of Species

Lynn Margulis has been a maverick all her life. Early in her career she shocked her biological colleagues by arguing that the mitochondria that power our cells and the chloroplasts that let plants transform solar into chemical energy once were free-living bacteria. As soon as scientists could isolate and decode the scraps of DNA in those vital organelles, they found that she was right. Margulis went on to develop her Serial Endosymbiosis Theory, which attempted to trace the development of all creatures with nucleated cells, from yeasts to humans, to a series of genetic mergers between different kinds of organisms. According to Margulis, all the familiar family trees of life, which show only diverging branches, are wrong. Ancient roots and current branches cross and merge to produce new species. To Margulis, nature is far more promiscuous and much more creative than most biologists dream.Her new book, Acquiring Genomes: A Theory of the Origins of Species, extends and deepens that argument. Margulis sets out to prove that new species rarely if ever appear as the result of mutation, isolation, genetic drift, or population bottlenecks--the meat and potatoes of neo-Darwinism. Instead she maintains that the major engine of evolutionary change, the source of most of the new forms that natural selection edits, is symbiogenesis--the acquisition of whole genomes as the result of symbiotic associations between different kinds of organisms. (Knowing that some people will seize on her thesis as an attack on the theory of evolution as a whole, Margulis makes it clear that she fully supports Darwin's great discovery of the mechanism of natural selection. She simply thinks that neo-Darwinists have failed to recognize the enormous creative power of genomic mergers.)Readers who are familiar with Margulis' earlier works will recognize her vivid, personal and sometimes impressionistic writing style. I found this book, co-authored by her son, Dorion Sagan, to be clear and accessible. Starting with Chapter 9, where Margulis presents her latest ideas on the symbiotic origin of the nucleus itself, things get a bit more technical. Margulis makes every effort to help readers through the thicket of important, but at times tongue-twisting terms, and supplements explanations in the text with an excellent glossary. Margulis also presents the findings of several other researchers whose work supports or relates closely to her own.Readers may or may not close the book convinced that Margulis is right and the neo-Darwinists are wrong. But they will come away with a vastly deeper understanding of the pervasive nature and power of the microbial world, and of symbiosis. Margulis reveals a hidden side of nature, in which microbes have generated most if not all of life's metabolic machinery, in which vastly different life-forms consort in a myriad of ways, and in which the acquisition of entire genomes provides the raw material for great evolutionary leaps. Anyone with a deep interest

Acquiring Genomes: A Theory of the Origins of Species written by Lynn Margulis and Dorion Sagan will definitly open your eyes and is on the cutting edge of how species are formed. This is one of those groundbreaking books that trys to answer one of Charles Darwin's long standing mysteries... how do species originate. Darwin could never quit put his finger on the answer, he was close and I'm sure with time and the right equipment, like what is available today, he might have even solved this nagging question.Margulis has been working on this same question for the last thirty years and she makes a very convincing argument, symbiotic merger is the main thrust of her thesis in this book. This book has some real mind-spinning ideas and you'll have to know some biochemistry, biology, chemistry, cell-biology to prepare yourself for a provocative wild ride through this book as some of the material directly challenges the assumptions that we hold about diversity in the living world.Margulis has for many years been the leader in the interpretation of evolutionary entities as the products of symbiogenesis. Symbiogenesis is the major theme of this book. The authors show convinvingly that an unexpectedly large proportion of the evolutionary lineages had their origins in symbiogenesis. Ok, I know some of you are saying what is symbiogenesis, well it's the combination of two totally different genomes form a symbiotic consortium which becomes the target of selection as a single entity. This is achieved by the mutual stability of the relationship, symbiosis differs from other cases of interaction such as carnivory, herbivory, and parasitism.Now, that I've said all of that, you realize that this book can get pretty deep at times, but the author has a pleasent styled narrative, always keeping the reader involved. Prehaps the greatest merit of this book is that it introduces the reader to the fascinating world of microbes, delving into providing an enthralling description of protists and bacteria.I found this book to be most enlightening about the enigma of evolutionary biology and how species are formed, comprehensive in scope and supported by scientific theory. This book will make you think. If you want to know about the cutting edge of evolutionary thinking then this is the book for you. To realize that everything on earth is inter-related and that life will carry on when faced with tragedy.

Lynn Margulis and Dorion Sagan continue their series of books on highlighting Margulis's evolving and elaborative theory on evolution. Margulis, with her symbiosis concept, is science's only significant spearhead on the creation of Darwinian evolutionary theory not strictly within the vague limits of Darwinian framework. This book gives us hints on her progress to moving closer to understanding the origin and evolution of eucaryotic mitosis and meiosis mechanisms.In the book, Sagan and Margulis outline their major objections with neo-darwinian orthodoxy: the notion of mutation and its inherent implications, and argue that its current role in theory is misguided and overemphasized. They argue, rightfully so, the concepts of symbiogenesis and Gaia give much better traction to explaining change from a procaryotic world to the current world of the living than the doctrines of neo-darwinian selection via mutation.Margulis and Sagan give a interesting account, and more importantly, several detailed examples of symbiosis, where the genome has clearly changed. Whether or not one is familar with Margulis's work, the accounts are enlightening, although I wouldn't recommend this book as an introduction to Margulis's symbiosis and Gaia metaphors, it gives enough to wet the appetite for more. I would recommend Microcosmos as better introductory book to get a better glimpse of the scope and revolutionary nature of Margulis's ideas. If one is interested in other details, her other books, such as the Symbiotic Planet are worth reading.Clearly the most important part of the book, besides a few more of her and Dorion's insights into Gaia, is the report on her latest publishable material on evidence of the steps from procaryotic to eucaryotic organisms. She concentrates more on her evidence for the first major symbiotic pairing (amitochondriates) which eventually leads to the mitosis and meiosis mechanisms. Her detailing of karyomastigont and akaryomastigont mechanisms and their relations, gives one a better understanding of some of the major steps that most likely occurred from the transition from gross bacterial genetic mechanisms (e.g., plasmids, bacteriophages, and conjugation) to the full blown eucaryotic mitosis and meiosis mechanisms. Obviously, despite their compelling evidence, there looks to be a great deal of work to done to fill in gaps between the connected dots. But Margulis and Sagan provide an entertaining and informative overview on some of the issues entailed in determining the details.The book is a tantalizing look at the edge of science, for if one is informed, one can see some interesting signposts ahead. The only problem I have with the book is once you start looking beyond the edge, you realize indeed Margulis has only a few explorers with her, and they haven't gotten very far. But that's the nature of science, isn't it.

Numerous titles have explored how species evolved; but there's not a single example among them of species arising by a gradual accumulation of random gene mutations. Acquiring Genomes poses a new theory of development, maintaining that individual gene mutations are minor events and that big evolutionary changes occur when different types of organisms merge with their genomes - all the genes they possess. An intriguing discussion and convincing argument emerges.

Acquiring Genomes will not appeal to all readers. First of all, the authors clearly have little use for current dogma, that is: local mutations in chromosomes fuel evolution and, particularly, speciation. I received my degree in Zoology back in a time when paleontologists called `em like they saw them, and lock-step conformity was a sign of a weak mind. I learned, in 1975, that there is precious little in the fossil record to support the concept of gradual evolution. Apparently, that has not changed.Prof. Margulis' book also assumes a reader with a broad scientific background , largely in areas considered "old fashioned" in the 21st century. She demands an upper college level familiarity with invertebrate biology, physiology, microbiology, ultrastructure, biophysical chemistry, metabolic pathways and *GASP* thermodynamics. Then she integrates molecular biology and genomics, as needed, into the picture, to make a very convincing case for symbiogenesis. She also evokes wrath for bringing up the name of Jean Baptiste Lamarck, which is sure to raise a red flag in neodarwinist circles. Last, she does not refute the contribution of neodarwinists, she simply tries to put them in perspective.The founding premise is that mutations constantly occur during the natural history of a species. Many experiments suggest 99% of these mutations are either silent or deleterious. Therefore, they probably cannot be counted on to drive evolution to improve on a species, let alone create new ones. Instead, a more likely pathway is for two species, with one bacterial, one eucaryotic, to coexist if it causes them to have a survival advantage when they do so. If it is in both organisms' best interest, this coexistance becomes more intimate, and can lead to the eucaryotic organism taking the smaller genome into its chromosome and making one very new and improved species. This, and many intermediate stages, are seen among invertebrates, such as Geosiphon pyriforme, a hybrid organism with a fungal (Endogone) and a cyanobacter (Nostoc) ancestor. The Geosiphon has retained the ability to fix carbon dioxide and nitrogen, receiving one multigene trait from one ancestor and the other from the partner species. Examples like this are why a reader needs a strong invertebrate biology background in order to appreciate these chimera. She ends the discussion with another tantalizing mechanism, called the kinetichore reproduction theory. In this process, environmental stress can lead to an additional round of kinetichore - centromere reproduction in an organism's chromosomes which leads to twice as many half-sized acrocentric chromosomes. Fertilization where one donor has undergone this alteration still leads to diploid progeny, but the diversity generated is the engine for adaptive radiation of species.Obviously, I am not ashamed to say I have bought into her arguments. If I were an academic scientist, I could have a field day testing some of her hypotheses. Ins