Science 6 September 2013:
Vol. 341 no. 6150 pp. 1055-1055
DOI:10.1126/science.341.6150.1055
News & Analysis

Evolution Heresy? Epigenetics Underlies Heritable Plant Traits

Elizabeth Pennisi | 7 Comments

A study presented at an evolutionary biology meeting found that heritable changes in plant flowering time and other traits were not the result of DNA sequence changes but chemical modifications to the DNA.

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Critics who think undiscovered genetic variation might really be in play instead of epigenetic effects were dealt a severe blow to their theoretical approach on 9/13/13. In the first experiment to ever address whether fixation of mutations occurred in the genome, no evidence for fixation was found in the model organism C. elegans. See: Chelo et al. "An experimental test on the probability of extinction of new genetic variants."

Evidence for the epigenetic effects of olfactory/pheromonal input on fixation of new alleles was reported in "Nutrient-dependent/pheromone-controlled adaptive evolution: a model." This evidence includes fixation in "grazing" nematodes: C. elegans, compared to "predatory" nematodes: Pristionchus pacificus,(with their nutrient-dependent morphogenesis of teeth sans mutations theory).

It has become more apparent now than it was even just a year ago, that epigenetically-effected changes in base pairs lead to amino acid substitutions. One substitution can enable distinctive morphogenesis (e.g., of teeth and of plumage color or hair). And morphogenesis is clearly linked to natural selection via protein biosynthesis and metabolism of nutrients to species-specific pheromones that control reproduction in species from microbes to man.

Thus, the focus MUST rapidly change to the nutrient-dependent controlled physiology of reproduction in plant and animal species, instead of waiting for someone to discover undiscovered genetic variation or unknown molecular mechanisms that might really be in play instead of epigenetic effects on the conserved molecular mechanisms of plants and animals.

Submitted on Mon, 09/30/2013 - 12:32

In the face of now extant evidence of the inheritance of acquired characters, many scientists are still very slow to gaze through a new prism of evolutionary thought. The last sentence in this article sums this up nicely, "people are really stubborn about accepting that that's possible." Dare I say that anyone who wishes to publish a peer reviewed article or a book mentioning the word 'Lamarck', it is not likely to be accepted. Herein lies the problem, the debate has never really been an open one.

Submitted on Fri, 09/20/2013 - 21:05

Thanks for mentioning that, Robyn. Last week I was told by a co-editor of a prestigious neuroendocrinology journal to not bother submitting another manuscript because the reviewers generally consider an author's recent scientific accomplishments when deciding on the acceptability of a manuscript for publication. The added insult was a comment about my lack of primary scientific contributions in the field of neuroendocrinology despite our 1996 publication of From Fertilization to Adult Sexual Behavior and an award-winning publication in 2001: Human pheromones: integrating neuroendocrinology and ethology.

Earlier rejection of what became "Nutrient-dependent pheromone-controlled adaptive evolution: a model," was quick and readily recognizable as an attempt to maintain focus on steroidogenesis with no mention whatsoever of epigenetic effects of olfactory/pheromonal input on gonadotropin releasing hormone, a decapeptide that's been conserved across the past 400 million years of vertebrate evolution as a link from glucose and amino acid uptake to the pheromone-controlled physiology of reproduction.

If I had ever been in a publish or perish environment, I would have perished. As you say, "...the debate [about cause and effect] has never really been an open one." For some, mutations will always be the driver of evolution because they have never considered the fact that the physiology of reproduction is nutrient-dependent and pheromone-controlled. Considering the biological facts now might be academically embarrassing. Thanks again.

Submitted on Mon, 09/30/2013 - 12:59

It is also a no-brainer that there is plenty of variable epigenetic regulation for selection to work on in plants. The title of this piece and the underlying skepticism it reports are incredibly uninformed. It would be unbelievable if epigenetic regulation were NOT involved in the evolution of plant traits.

Submitted on Sat, 09/14/2013 - 18:19

Epigenetic modification in bad press to Lamarck warranted

With reference to E. Pennisi’s News and Analysis article “Evolution Heresy? Epigenetics Underlies Heritable Plant Traits” (6 Sept, p. 1055), it is unfortunate to note that the term Lamarckism is still used with complete disdain even when accumulating evidence in modern biology clearly supports epigenetic inheritance in plants and animals (1-4). Irrespective of whether or not this unconventional, non-genetic inheritance plays an important role in evolution, the very revelation that environmental effects on the phenotype can be transmitted to future generations confronts us by asking if Lamarckism is so incorrigible a theory that it shall remain completely discredited in perpetuity! Take for example the recent finding that toxin induced liver damage in rats results in the development of resistance to the same across generations, with the evidence that a soluble factor in serum mediates liver to sperm communication (5). Does this kind of “inheritance of acquired characteristic” not at once remind us about the Lamarckian idea? If the answer is in the affirmative then it is high time we stopped abusing Lamarck. It is no one’s case that the DNA of what the French Biologist brought to the fore around two centuries ago is now proven valid, but then at the same time he also deserves epigenetic modification for the better in the very bad press that he received throughout.

References:

1. B. A. Buckley et al., Nature 489, 447 (2012). 2. S. Rasmann et al., Plant Physiol. 158, 854 (2012). 3. L. Daxinger, E. Whitelaw, Nat. Rev. Genet. 13, 153 (2012). 4. J. P. Lim, A. Brunet, Trends Genet. 29, 176 (2013). 5. M. Zeybel et al., Nat. Med. 18, 1369 (2012).

Submitted on Fri, 09/13/2013 - 00:26

Note, we may have been the first to address molecular epigenetics in the context of hormone-organized and hormone-activated behavior. See: From Fertilization to Adult Sexual Behavior. Hormones and Behavior. 30 (4) 333-53.

Abhay Sharma now includes references to recent works that support cohesive thoughts on a new (old) approach to incorporating biological information into scientifically unsubstantiated theories about mutation-driven evolution, which has failed to incorporate the physiology of reproduction.

I will add a reference to my work that may help with integration of current information into a model of adaptive evolution based on biological facts that include the physiology of reproduction.

Nutrient-dependent/pheromone-controlled adaptive evolution: a model. Socioaffective Neuroscience & Psychology 2013, 3: 20553

The extension of our 1996 mammalian model to insects in 2000 and to their epigenetically-controlled life-stages in 2005 could have been expected to bring forward aspects of epigenetic effects on alternative splicings that are still somewhat in the background, but ever-present in the literature on precisely how the epigenetic "landscape" becomes the physical landscape of DNA in the organized genomes of species from microbes to man. That's why I think that the molecular mechanisms, which enable the epigenetic effects, are the same in plants.

Does anyone think the molecular mechanisms are different enough to allow for the mutation-driven evolution of any extant or extinct species?

Submitted on Fri, 09/13/2013 - 10:53

Is there a model for mutation-driven evolution in plants?

Article excerpt: "At the meeting, he described how he and colleagues tied DNA methylation patterns to heritable variation in flowering time and root length in different strains of the model plant Arabidopsis thaliana."

My comment: It is literally a "no-brainer" that plant reproduction is nutrient-dependent, as reproduction also is in all species of animals. If there a not a model of plant species diversification that attributes it to mutation-driven evolution, how can the molecular mechanisms of plant species diversification be extended to animal species diversification without chemical signals from plants that in animals are called species-specific pheromones?

Submitted on Thu, 09/12/2013 - 19:12