# Talk:Genetic assimilation

References are currently handled only as html links.  There should be a proper references section, and there should be more of them.
The evolutionary biology should be expounded further
I hope the graphic is seen as more whimsical than puerile, but it is at best incomplete; a second image showing how environmental conditions affect the primary and expressed phenotypes is still needed
Mike Serfas 23:17, 23 August 2006 (UTC)

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This review is transcluded from Talk:Genetic assimilation/GA1. The edit link for this section can be used to add comments to the review.
Reviewer: Starsandwhales (talk · contribs) 15:11, 26 April 2020 (UTC)

Hi! I'll be reviewing this article over the next few days. starsandwhales (talk) 15:11, 26 April 2020 (UTC)

Many thanks for taking this on. Chiswick Chap (talk) 15:21, 26 April 2020 (UTC)

So I'm confused. Is this when some outside influence alters genes? Or the outside influence changes the physiology?
See the diagram. Yes, Waddington envisaged and experimented with an external "shock".
I don't know how but could you clarify the Darwinian explanation? I don't know if it's just me with reading but I don't get what "The phenotype appears when the sum of gene effects exceeds a threshold that is lower with the perturbation than without." is trying to say.
I've tweaked it. However I fear that adjusting the wording is a non-terminating loop.
It makes more sense now.
"as a "told to the children" version of what I wished to say" --> single quotes inside the quote?
Done.
Is there some context as to who Erika Crispo is before she is quoted? Maybe something like "According to researcher Erika Crispo..." or something else that shows her authority on the subject.
Evolutionary ecologist.
Crispo's definition is very elegant and makes a lot of sense, maybe something similar in the lead would help with understanding
She's talking about genetic accommodation, however.
If the quote is about genetic accommodation, how does that help with the understanding of genetic assimilation?
She's saying that g. assim. is a kind of g. accom., which she defines as such-and-such. So, g. assim is indeed such-and-such, but while that bit of the story is relevant and more readily understood, it isn't the whole Waddington picture. Hope that's clear.
Ok.
I'm going to read the rest tomorrow, since I'm not sure how many of these issues actually stem from me not being able to understand the subject from reading the article just once. (I almost asked if you defined what canalization was, then reread and realized there was a paragraph on it that I didn't process)
Yes, the argument is tightly-knitted and one has to grasp all the pieces for it to work. Start from the fact that it is, despite all appearances, natural selection.
Is there information available about modern discussion about genetic assimilation? Is there consensus on how this occurs? Is it still being discussed?
'In natural populations' describes modern evolutionary biology research on the subject, at population, organ, and molecular levels respectively.
"making it uninteresting" Your words or George C. Williams'?
Williams. I wouldn't presume to comment, nor am I allowed to. Said 'in his view'.
"However, the preceding phenotypic plasticity need not be adaptive, but simply represent a breakdown of canalisation." Does this mean that the phenotypic plasticity is a step in the process of canalization?
No, the sentence is saying it's kind of the opposite, allowing development to break out into a new direction.
Canalization and canalisation are spelled differently throughout the article
Ah yes. We Brits nowadays usually use the -s- form but Waddington used -z-, so the spelling is Oxford English in fact. Fixed (just one instance).
In the example with the island tiger snakes are the large heads not genetically encoded for the younger snakes? Does it become genetically assimilated as the organisms grow older?
No, it's the age of the population (many snakes, many generations) not individual age.
I don't really know much about genetics, so my perspective is more of "what would someone on a wikipedia wormhole or who wanted to learn more about genetics after learning about Mendel or Darwin in school be able to understand?". The "In natural populations" section is the best for offering context on what this actually means, so I would suggest improving it by adding more information and elaborating on what is already there, or adding more examples.
They aren't easy to find: the topic has been something of a backwater since Waddington (and it was a curiosity even then).
Would an example for "handedness" be the spiral direction of snails?
Yes. The article gives the example of the human heart usually being on the left.
I feel like I'm out of my depth for this article, so I'm going to request a second person to review this.
Thanks for your work. Chiswick Chap (talk) 16:28, 2 May 2020 (UTC)


### Another review
Starsandwhales, as you requested a second opinion and the nominator suggested I take a look at the article, I will be happy to take over this review after a week or so. I have intermediate level knowledge of genetics so I may fit this role, and I feel a complete review is in order. Let me know if this is fine. Cheers, Sainsf · (How ya doin'?) 12:21, 11 May 2020 (UTC)

Many thanks. Note that the reviewer asked for someone actually to take over. Chiswick Chap (talk) 13:10, 11 May 2020 (UTC)
I had seen their comment, but I wished to notify them formally before I begin my work here. Cheers, Sainsf · (How ya doin'?) 13:36, 11 May 2020 (UTC)


#### General checks
No dablinks, broken external links or copyvio concerns
Noted.
Duplinks: phenotype (A Darwinian explanation), natural selection (Neo-Darwinism or Lamarckism?)
Gone.
Sourcing and citations:
Refs 8, 9, 13, 14 need proper formatting
Formatted.
All book citations need locations
Not required for GA.
No navboxes or something like Template:Evolution that can be used in this article?
Added, and tweaked the template.


#### Prose and coverage
Link phenotype, embryo, ether in the lead.
Done.
I wonder if we can find a good link for "genetically encoded", or just link "genetically" maybe? (Optional)
Not sure if that would help.
The classic example of genetic assimilation was a pair of experiments Are there other such examples, which may need "the" to be changed to "a"? And why "was", isn't it still a notable example?
These were what started the whole thing so they'll never be replaced. The "was" refers to these historic events.
While the article will be inevitably a bit tough for a lay reader to understand (plus this is not the Simple English wiki), we can try to explain a few terms in places like "a bithorax-like phenotype (a homeotic change)" where it almost goes over the head. Could we add something besides that connects "homeotic change" to an organ to organ transformation without going into details like homeotic genes? I like the explanation for halteres.
Not sure that adding more words will make things simpler; the best the new reader can do is read around the bluelinks, slowly.
Why do we have citations in the lead? Are they really necessary?
I think so in this case as anything with Lamarckian in it is controversial.
Conrad H. Waddington's classic experiment...second thorax It seems as if the 1942 expt alone is the classic one, and not the pair. Another point is when you start with the main text, it might be better to state the method first and then the result (as in the lead) else it sounds a bit too sudden (at least to me) for the introductory part of the article. Also, the "developing" bit is missing in the lead, maybe you would like to include it there? I would recommend something like this in the main text - "Conrad H. Waddington's classic experiment (1942), in which (developing?) Drosophila fruit fly embryos were exposed to ether, induced an extreme environmental reaction in the embryos – a proportion of embryos developed a radical phenotypic change, a second thorax."
Well, the 1942 experiment was for a decade the one-and-only; but the second one joined it as Waddington's definitive statement of what he conceived GA to be. And all live embryos are developing... I understand your wish to simplify, but bithorax is a gene (see next) so circumlocuting is risky. I've tweaked the text slightly.
Oh, I didn't realize bithorax refers to a gene, I thought it is the name of a body structure like thorax. No problem, changes look good. Sainsf (t · c) 11:16, 22 May 2020 (UTC)
Why is bithorax in italics here? It is in normal font in the lead. Also this term needs to be linked and introduced well like it was in the lead (" producing a bithorax-like phenotype")
It's conventional to use italics for names of genes, not only on Wiki. Fixed the mention in lead, well spotted.
Why is cross-veinless italicized here and later? Not sure if it is that important for emphasis
As above.
Waddington called the effect he had seen genetic assimilation You may want to put "genetic assimilation" in quotes when it is introduced in the main text as a newly coined term
Done.
epigenetic landscape maybe link epigenetic?
Done.
becomes entrenched or canalized Maybe put canalized in quotes as it is the term Waddington proposed
Done.
the new canal continues to attract developmental trajectories I didn't get how it "attracts" trajectories
Tweaked wording. The idea is that the entrenched valley or footpath becomes easier to follow, and indeed if you're walking not in that groove you tend to fall into it and keep going inside it. Of course it's just a metaphor (if I may venture a bit of OR); what Waddington was lacking was a precise evo-devo account.
Thanks, got it and the text is simpler to follow now. Sainsf (t · c) 11:16, 22 May 2020 (UTC)
After reading this explanation, I wonder if we should say something like "in response to a 'pressing' environmental condition", as only heavy perturbations like ether and heat bring about this process?
Yet another metaphor ... not sure that would help. Already said "major perturbations".
purely quantitative genetics explanation Shouldn't it be "genetic" like quantum mechanics would be written as "quantum mechanical"?
I think the analogy would be with "physics" where losing the -s would be surprising.
that threshold is lowered by the perturbation How exactly?
Not for me to say; it's ex hypothesi, "the story runs...". Text already says "is presumed to be" in previous sentence, which is part of the same story. Tweaked to say "If .. [then]" which possibly helps.
Continued selection under perturbation conditions "perturbed"?
perturbing, perhaps. It's all marginal.
frequency of the alleles Link alleles, or probably link it all to allele frequency
Done.
Continued selection under perturbation ...requiring the heat shock So tell me if I understood this correctly - as disturbances lower the threshold for a phenotype it becomes more common in the population so the allele frequencies that lead to the genotypes which result in these phenotypes obviously increase in the population. But what is the "higher" threshold here? Is there not just one threshold that perturbations help in lowering?
Ok, removed "higher". It means the threshold in the absence of perturbation, but we've already said that at least once in that sentence.
I understand why the section is named "A Darwinian explanation", because it connects to selection, but I think "Darwinian" should be included in the section somewhere so that a lay reader doesn't get confused
Added.
I have not seen questions in section headings like "Neo-Darwinism or Lamarckism?", I don't think it is against a policy guideline or unencyclopedic but would be good to confirm this.
Dropped the punctuation.
Link Neo-Darwinian. Link inheritance to inheritance of acquired characters
Linked the first. The second is an overlink of Lamarckian.
Introduce Adam S. Wilkins
Done.
A short explanation of phenotypic plasticity would be a good addition as it is discussed a lot later
Added.
Introduce J. M. Rendel
Done.
Explain or link mutation bias
Linked.
After reading through the whole article I think the lead should mention that the term was coined by Waddington, that there have been criticisms of the theory, and also add at least one example other than the flies. Also, this line "Genetic assimilation overcomes the barrier to selection imposed by genetic canalization of developmental pathways" is quite important and it would be excellent if it could be simplified (the concept of canalisation is tough to understand).
A bit sceptical of simplifying, it tends not to work on Waddington, but have added to the lead.
The rest looks good to me. Thanks for this really interesting read, your writing on this confusing topic is especially praiseworthy. Thanks also to Starsandwhales for the things they pointed out and helping in simplifying the material. Cheers, Sainsf (t · c) 08:53, 22 May 2020 (UTC)

I am happy with the changes, especially the lead which to me looks much better now. All comments of the previous review have also been addressed. I believe this article meets all the GA criteria now, promoted :) Sainsf (t · c) 11:16, 22 May 2020 (UTC)