I had a chance to participate in Lynn Margulis
's blog tour
(also see our previous coverage of Dr. Margulis on this blog
). The blog tour was held today at Memoirs of a Skepchick
. Dr. Margulis has specialized in speciation through symbioses, so I thought this would be a great chance to ask a question that has been on my mind for a while:
In “symbiotic planet” you seemed to indicate that symbioses might be the driving factor behind speciation and novelty in life history. However, in many cases, you seem to restrict your arguments to the origin of eukaryotes and other microorganisms. I’m personally more curious in the application of these ideas in present biology. Do we know the mechanisms of symbiotic establishments in the wild? What interesting symbioses have we observed, and what mechanisms were involved? Scott Gilbert has done some interesting reviews of biological phenomena in predator/prey relationships, where, during development, a prey can detect its predator in the environment and develop accordingly. Has any such mechanism been established for symbiotic relationships?
In response, Dr. Margulis gives us several interesting things to read. I've added in links to her response to help locate the materials should my readers be interested (post is also slightly edited for spelling and formatting):
Jonathan BartlettI never say anything “is interesting”..except to me or a colleague, family member or friend, but I love your question anyway.
Do we know the mechanisms of symbiotic establishments in the wild? What interesting symbioses have we observed, and what mechanisms were involved?
First: Bacteria, including archabacteria, can mate either by cell to cell contact or by dropping one’s DNA into the wetness to be taken up by the other. All bacteria will rather mate than die when that is the choice. Since you can put them in the refrigerator in the evening and make them be another species by morning I agree with Sorin Sonea (book: Prokaryotology, Universite Montreal Press) that they have no species in the sense nucleated organisms have..Then we work with speciated protists that have no sexual life histories but surely that have species identity.
Jonathan, there is a fine literature dating back to the mid 19th Century that has been summarized in several books: Evolution by Association: a History of Symbiosis research (Jan Sapp) our book Acquiring Genomes: A Theory of the origins (s, plural) of species (Margulis and Sagan, 2002 Basic Books) and now we found that most of the classical well studied cases were known to Boris Kozo-Polyanski in his book A new Principle of Biology [no link found] (he meant evolution by symbiogenesis) in 1926. This book is nearly all translated by Victor Fet, a biol. prof at Marshall univ in Huntington W V.
By no means are these ideas only in the microcosm. What is a cow (or a bison) unable to eat grass? A starved cow. What is a subterranean termite unable to eat and digest wood? A dead termite. Both these types of animals owe their existence to great communities of highly specific symbionts that digest their foodstuffs, make them change their bodies (over time, of course). The rumen, the hindgut. The literature is vast and so detailed that in 1924-26 K-P wrote a book explaining this..he united Darwin's “natural selection (which only ELIMINATES life forms, does not create them) with SYMBIOGENESIS that does create new species in the same genus. Other modes of species change include: polyploidy in plants, hybridization in marine larvae, karyotypic fissioning (centromere reproduction) in mammals and several other modes [emphases mine]. All are far more significant for the generation of new species than “random mutation”. Of course random mutations hone and refine the bigger hereditary processes but there is no evidence I know of that proves that random mutation GENERATES evolutionary novelty..i.e. new species. All this is detailed in the books I mentioned and see the ISS (International Symbiosis Society) and its journal called Symbiosis.