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Diatom Evolution a Mystery

first_img(Visited 293 times, 1 visits today)FacebookTwitterPinterestSave分享0 A science writer is sure diatoms evolved, even if their origins and intricate designs are major mysteries.Michael Gross, a science writer at Oxford, wrote a feature story for Current Biology called, “The Mysteries of the Diatoms” (Current Biology, Volume 22, Issue 15, R581-R585, 7 August 2012).   Gross knows that diatoms are extremely successful and diverse, very important for the carbon cycle, and beautiful to look at, but said scientists still know little about them.  One of the chief mysteries is their evolution:Diatoms — single-celled algae typically enshrined in a cell wall made of intricately laced silica — have fascinated researchers with a whole range of mysteries, from their evolutionary origins through to their morphogenesis and reproduction. They entered the plant kingdom rather late in evolution, and through an unusual entry. Researchers believe they are secondary endosymbionts, meaning that their precursor was a eukaryote that engulfed another eukaryote, resulting in a quadruple membrane around the chloroplasts the diatom gained from this act of piracy.The evolutionary success story of diatoms only begins some 200 million years ago, but they have spread around the globe and diversified into hundreds of genera and around 100,000 species in this short fraction of the geological timescale. Today, they are present wherever there is liquid water, in the oceans, in freshwater, and even in soil. They have already played a significant role in the global cycles of carbon and nitrogen, and are responsible for large sediments of silica including diatomaceous earth.In the article, Gross described many amazing facts about these microbes that live in glass houses:“they have a very efficient way to dissipate excess solar energy, known as non-photochemical quenching.”“In a time span of less than 200 million years, diatoms have branched out into a multitude of species, which can be as genetically different as humans and fish.““While we might want to call diatoms ‘plantimals,’ these things are much more complex than we think,” Chris Bowler says.“Like animals, for instance, diatoms possess a complete urea cycle…. the cycle enables diatoms to recover quickly after prolonged periods of nitrogen limitation.”“…diatoms have a huge influence on geochemical cycles and our climate.”“Diatoms fix as much carbon dioxide as all the rainforests of the world combined….”“The silica frustules with their intricate nanoscale patterns can make any nanotechnologist jealous. Nature can produce such structures at ambient temperature and under benign conditions, an achievement that our technology cannot match yet.”“Diatom adhesives are of interest for two opposite reasons — some may want to mimic bioadhesives like these to produce better glues that work under difficult conditions, for instance under water. Others want to stop diatoms from sticking to things under water, such as ships.”Considering these are widespread, common organisms we can study right under a microscope, surprisingly little is known about them, Gross said.  For instance, the in-depth study of model organisms like water cress and E. coli hasn’t helped scientists understand the molecular physiology of diatoms.  The growth (morphogenesis) of their intricate glass patterns is not understood.  Their role in climate modulation is poorly understood.  It’s not that scientists have not tried; the mysteries of diatoms have so far proved intractable.One thing Michael Gross seemed profoundly confident about, though, was his belief that they evolved from non-diatoms.  This extended not to his endosymbiotic theory but to their subsequent ability to evolve other capabilities that stump human engineers.  He spoke glibly about how “diatoms evolved thicker and denser cell walls and spread across the oceans,” speaking at one moment about the mystery of their “evolutionary origins” but then their “evolutionary success story.”  It didn’t seem to bother him that in half the time horseshoe crabs remained static, diatoms diversified into 100,000 species with genomes that differ as much between them as fish differ from humans.  Evolution works in strange ways.There is no such thing as an evolutionary success story.  Evolution, being mindless, purposeless, and aimless,(see clarification on Evolution News) could not care less about what thrives and what goes extinct.  If the whole world went extinct, “evolution” (whatever that fictional being represents), would yawn and move on.  By using the word success, Gross exposes himself as an unevolved human who cares.In the 12/19/2007 entry, we used the nonsense word gribbleflix as a substitute for evolution, and it worked in the same manner – it explains everything without needing to explain anything.  Readers are encouraged to re-read that commentary to understand how Michael Gross, and the accomplice Current Biology, employed evolution as nonsense masquerading as explanation.last_img

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