Note: This is a guest post by Virgil Cain. I have left it as is, with just a couple of typographical corrections. See my brief comments and caveats at the end.
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By Virgil Cain
In 1997, “Not By Chance” by Lee Spetner was published. In it he argued for a “non-random evolutionary hypothesis” which had a mechanism of “built-in responses to environmental cues” at its heart. Some mutations happened just when they were needed. And some happened at just the right place to be effective. And even others, called transposons aka jumping genes, carried within its DNA coding sequence the coding for two of the enzymes required for it to be able to move around.
A transposon has in it sections of DNA that encode two of the enzymes it needs to carry out its job. The cell itself contributes the other necessary enzymes. The motion of these genetic elements about to produce the above mutations has been found to be a complex process and we probably haven’t yet discovered all the complexity. But because no one knows why they occur, many geneticists have assumed they occur only by chance. I find it hard to believe that a process as precise and as well controlled as the transposition of genetic elements happens only by chance. Some scientists tend to call a mechanism random before we learn what it really does. If the source of variation for evolution were point mutations, we could say the variation is random. But if the source of variation is the complex process of transposition, then there is no justification for saying that evolution is based on random events. (Dr Lee Spetner “Not By Chance” page 44)
Barbara McClintock was laughed at when she elucidated her discovery of jumping genes for the simple reason they have the characteristics of being under some control.
The “non-random evolutionary hypothesis” applies to individuals- individuals do evolve, ie change at the genetic level.
Enter 2006 and the publication of “Evolution in Four Dimensions” by Eva Jablonka and Marion J. Lamb and the elucidation of epigenetics, ie “built-in responses to environmental cues”. I couldn’t stop thinking about “Not By Chance” wondering if Lee Spetner had read it and if he felt vindicated by it. Organisms are designed with different levels of possible variation. For example there is a possible variation with how the existing genes get expressed and another is changing the actual genes such that it changes the proteins. Change the regulation of the gene or change the gene itself. Lenski’s E. coli changed the regulation of a gene by duplicating it and putting it under control of a promoter that allowed for it to be expressed in an aerobic environment. It was an environmental factor, the presence of O2, which repressed the gene. It was another environmental factor, the presence of citrate, which made getting that gene expressed beneficial.
“Evolution in Four Dimensions” is a good book to have around. They describe experiments of microsurgery onParamecium. A piece of the cortex was cut out, rotated 180 degrees and reinserted. The offspring inherited the change. (Lamarck 101)
Then came 2011 and the publication of “Evolution: A View from the 21st Century” by James A. Shapiro (a colleague of Dr. McClintock) and even more support for the “non-random evolutionary hypothesis” and “built-in responses to environmental cues”. Again I wondered about Dr Spetner and if he was reading this book too. The book starts out talking about “Sensing, Signaling, and Decision Making in Cell Reproduction” and has a table of “Examples of Targeted Genetic Engineering”. Of course he thinks it all evolved because obviously that is what evolution does or maybe due to coercion from fellow U Chicago Professor Jerry Coyne that is what he had to say to prevent being attacked. But I digress, the book is well worth the read and there is evidence that some mutations happen just when they are needed. They are not random with respect to fitness; it is the organism doing some rearranging to stay fit.
In 2014 Lee Spetner’s “the Evolution Revolution”- Why Thinking People are Rethinking the Theory of Evolution” was publisged and although he doesn’t cite “Evolution in Four Dimensions” he does cite Jablonka’s work on epigentics. He does cite both Shapiro’s work and the book “Evolution: A View from the 21st Century”.
Moving along, Lee Spetner cites several cases in which evolution happened much too rapidly to be accountable for genetic accidents and [instead] have all the appearances to have been triggered by the environment:
1- Studies on daisy and daisy-like plants and their seed dispersal mechanisms. On the mainland the seeds are packaged such that the wind can carry them great distances- little white fluff-balls floating endlessly on a warm summer’s breeze. But on a small island that isn’t a good strategy. Once transplanted from mainland to small island they lose that seed-dispersal ability in just a few years – Cody & Overton (1996) “Short Term Evolution of reduced dispersal in Island Plant Populations” Journal of Ecology 84(1): 53-61
2- Rhagoletis pomonella– went from feeding solely on hawthorn, to apples and onto cherries, roses and pears. Studies show the hawthorn and apple flies differ genetically
3- Guppies- Cichlid fish prey on large mature guppies and killifish prey on small immature guppies. When cichlids are their main predator in the environment the guppies mature earlier and have many small offspring which evade the cichlids. When killifish are their main predator the guppies mature late and have fewer but larger offspring which can evade the killifish. He cites several papers that have Reznick as one of or the main contributor
4- Lizards and rapid evolution- Losos (2001) “Evolution: A Lizard’s Tale” Scientific American 284(3): 64-69; Losos and Schoener (1997) “Adaptive differentiation following experimental island colonization in Anolis lizard”Nature 387: 70-73; and other articles by Losos and/ or Schoener
5- Finches- Lee Spetner was here on UD and posted this one See here
He reiterates his hypothesis is different, in that with his, individuals do evolve.
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Comments by Eric Anderson:
We have been discussing this issue, largely as a result of this thread. Specifically, wd400 claimed that there are no examples of genetic change that are non-random with respect to fitness, a key assertion of Neo-Darwinian theory. As a result, I invited Virgil Cain to draft a brief OP on Spetner’s new book, as Spetner discusses several examples of genetic change that are non-random with respect to fitness.
I would note a couple of additional points, to help avoid side roads and irrelevancies.
First, my original OP and the points raised therein stand largely independent of whether there are non-random genetic changes. I raised it as an open issue and as one of the things that Reznick had perhaps not considered. Second, on a related thread wd400 made a statement suggesting that heritability of a trait somehow demonstrates that the trait could not have arisen in response to environmental factors. This is clearly incorrect and demonstrates confusion about the issue at hand, which is how the trait arose, not whether it can be subsequently inherited. Third, I would note that the finch beaks discussed in the other thread are in interesting example, but perhaps not the most compelling example. Don’t get hung up on the finch beaks in determining whether there are any examples of non-random genetic change.
While there are other interesting issues at play, on this current thread I would ask that commenters focus on the specific issue at hand:
Are there genetic changes that are non-random with respect to fitness?