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posted by mrpg on Saturday February 23 2019, @06:36AM   Printer-friendly
from the algae dept.

The transition took place over the course of 50 weeks and was caused simply by the introduction of a predator to the environment. Time-lapse videos are available in the supplementary info.

The transition from unicellular to multicellular life was one of a few major events in the history of life that created new opportunities for more complex biological systems to evolve. Predation is hypothesized as one selective pressure that may have driven the evolution of multicellularity. Here we show that de novo origins of simple multicellularity can evolve in response to predation. We subjected outcrossed populations of the unicellular green alga Chlamydomonas reinhardtii to selection by the filter-feeding predator Paramecium tetraurelia. Two of five experimental populations evolved multicellular structures not observed in unselected control populations within ~750 asexual generations.

De novo origins of multicellularity in response to predation


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  • (Score: 1, Disagree) by Bot on Saturday February 23 2019, @07:10AM (7 children)

    by Bot (3902) on Saturday February 23 2019, @07:10AM (#805493) Journal

    it's darwin theory going down the drain.
    Darwin discovered the mechanism, and used occam's razor to imply that mutations were impersonally random and natural selection did the job over million years. Now you can maybe postulate a random set of mutations that take into account the presence of a threat to retransform the algae into a multicellular organism (there must have been a previous attempt, then reevolution into single cell, there is no way you synchronize everything in 50 weeks of random mutations). But, it's like studying card players and claiming a professional player throws cards out first randomly, then merely remembering his successes, and that he is winning a tournament because his cards end up better and someone is going to win the tournament anyway. All because of your religious application of occam's razor. There is something else, called awareness of the game.

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  • (Score: 0) by Anonymous Coward on Saturday February 23 2019, @10:46AM (3 children)

    by Anonymous Coward on Saturday February 23 2019, @10:46AM (#805529)

    there is no way

    there is no way people can ignore reality, and yet, there you are! Fuck!

    https://en.wikipedia.org/wiki/E._coli_long-term_evolution_experiment [wikipedia.org]

    Like how come evolution works, randomly, like eating food that they never had genes for eating before? Oh yes, magic. There is no way I can accept I was wrong!

    • (Score: 2) by Bot on Saturday February 23 2019, @12:37PM (2 children)

      by Bot (3902) on Saturday February 23 2019, @12:37PM (#805550) Journal

      Excuse me but "even though several lines of evidence suggested that much of the accumulation was beneficial, rather than neutral" doesn't strike me as a counterpoint.

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      • (Score: 2) by HiThere on Saturday February 23 2019, @05:47PM (1 child)

        by HiThere (866) Subscriber Badge on Saturday February 23 2019, @05:47PM (#805666) Journal

        Sorry, but you shouldn't accept the wiki page as an authoritative report on the experiment. It's been simplified for public consumption, and was probably written by either an intern or a reporter. Other reports on the experiment that I've seen earlier explained what kind of "convergent" beneficial mutations happened, how they differed, and why it's what you should expect to see. (OTOH, IIRC my source, also not a prime source, was a book by Dawkins. So if you're offended by his religious views you can reject him as a biologist.)

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        • (Score: 2) by Bot on Sunday February 24 2019, @09:36PM

          by Bot (3902) on Sunday February 24 2019, @09:36PM (#806052) Journal

          You watch a videogame 3D FPS duel, and one of the two players seems to always get the good move, then you HAVE to theorize he might be wallhacking. If a statistical analysis says he might be just lucky, you don't need to proceed further.

          If there is a statistical analysis that finds some ratio of p of mutation depending only on IRL parameters and it models the result of the experiment, I am fine with it. It's been some years I keep telling that evolution is not a dual of creationism, but are orthogonal/independent. As for trusting Dawkins, it is irrelevant. This is a matter for the stats guys not the bio guys. The implicit (and therefore dangerous) assumption that mutations are impersonally random, which isn't even a religious matter but a matter of how the universe works (on planes beyond the physical maybe), can only be addressed by statistics.

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  • (Score: 3, Informative) by Immerman on Saturday February 23 2019, @04:50PM (2 children)

    by Immerman (3985) on Saturday February 23 2019, @04:50PM (#805626)

    Except evolution doesn't happen through the accumulation of random mutations. The initial gene mutations are random, but accumulation only occurs for those mutations that confer a survival advantage to the organism. Individuals with a mutation that gives them an advantage prosper and spread that advantage to their offspring. Mutations that confer a disadvantage cause those gene-lines to be rapidly culled from the population. The propagation of neutral mutations is entirely dependent on their chance occurrence in individuals with advantageous mutations, and will accumulate gradually, until some other mutation either eliminates them or utilizes them.

    Just because the source of mutation is random, that doesn't mean that the process of evolution is. There's also an incredibly detailed and at least semi-intelligent algorithm deciding which mutations are and are not desirable. It's called life. Those individuals that prosper and reproduce most prolifically have through their successes established that a mutation is desirable.

    I also don't think you properly appreciate the scale of the work being done here: It's not "only" 50 weeks - algae reproduce quickly, 50 weeks is about 750 generations. If they started with one single asexual individual, and never pruned the tree of life that it divided into with each replication, there would be 2^750 genetically distinct individuals by the end of the experiment. That's 10^145 individuals for every single atom out of the estimated 10^80 atoms in the known universe. With a tree of life that size, an *enormous* amount of variation can occur. What life does is constantly prune the least-promising branches, as measured by how well the DNA helps the current individual survive and prosper.

    • (Score: 2) by HiThere on Saturday February 23 2019, @05:52PM (1 child)

      by HiThere (866) Subscriber Badge on Saturday February 23 2019, @05:52PM (#805669) Journal

      Not quite. Most retained mutations are "neutral drift", meaning that in the current environment they have no effect. Some of them even only affect the likelihood of future mutations (some codons are more chemically stable that others that have the same transcription into amino acids).

      Now when the environment changes, some of these "neutral drift" mutations become significant. E.g., that's how we lost the ability to make vitamin C, or gained a third color receptor. (Well, the color receptor was a neutral gene duplication followed some time later by a mutation in what colors it was sensitive to. But it started off as a neutral change.)

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      • (Score: 2) by Immerman on Sunday February 24 2019, @04:05PM

        by Immerman (3985) on Sunday February 24 2019, @04:05PM (#805953)

        I was trying to give a 50,000ft overview of how random noise (mutation) fuels a decidedly non-random process (evolution), and figured neutral mutations weren't worth much more than an acknowledgment in that context.

        You make a good point that they serve as sort of a genetic "savings account" against sudden environmental changes though. In fact, it's actually an advantage that neutral mutations don't tend to spread throughout the species, instead drifting through minorities of the population more-or-less at random. That provides a great deal of genetic diversity across the species, some of which will likely become relevant, for better or worse, if the environment changes suddenly. In that sense it gives a species an evolutionary jump start towards evolving in response to major changes.