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Author Topic:   Galapagos finches
Elmer
Member (Idle past 6022 days)
Posts: 82
Joined: 01-15-2007


Message 100 of 104 (443631)
12-26-2007 7:46 AM


The neo-lamarckian mechanism
FYI--
Rebecca L. Young & A.V. Badyaev, 2007. Evolution of ontogeny: linking epigenetic remodeling and genetic adaptation in skeletal structures. Integrative & Comparative Biology 47(2):234-244. ABSTRACT. Evolutionary diversifications are commonly attributed to the continued modifications of a conserved genetic toolkit of developmental pathways, such that complexity and convergence in organismal forms are assumed to be due to similarity in genetic mechanisms or environmental conditions. This approach, however, confounds the causes of organismal development with the causes of organismal differences, and, as such, has only limited utility for addressing the cause of evolutionary change. Molecular mechanisms that are closely involved in both developmental response to environmental signals, and major evolutionary innovations and diversifications, are uniquely suited to bridge this gap by connecting explicitly the causes of within-generation variation with the causes of divergence of taxa. Developmental pathways of bone formation and a common role for bone morphogenetic proteins (BMPs) in both epigenetic bone remodeling and the evolution of major adaptive diversifications provide such opportunity. We show that variation in timing of ossification can result in similar phenotypic patterns through epigenetically induced changes in gene expression, and propose that both genetic accommodation of environmentally induced developmental pathways and flexibility in development across environments evolve through heterochronic shifts in bone maturation relative to exposure to unpredictable environments. We suggest that such heterochronic shifts in ossification can not only buffer development under fluctuating environments while maintaining epigenetic sensitivity critical for normal skeletal formation, but also enable epigenetically induced gene expression to generate specialized morphological adaptations. We review studies of environmental sensitivity of BMP pathways and their regulation of formation, remodeling, and repair of cartilage and bone to examine the hypothesis that BMP-mediated skeletal adaptations are facilitated by evolved reactivity of BMPs to external signals. Surprisingly, no empirical study to date has identified the molecular mechanism behind developmental plasticity in skeletal traits. We outline a conceptual framework for future studies that focus on mediation of phenotypic plasticity in skeletal development by the patterns of BMP expression.
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Replies to this message:
 Message 101 by RAZD, posted 12-26-2007 10:39 AM Elmer has replied

  
Elmer
Member (Idle past 6022 days)
Posts: 82
Joined: 01-15-2007


Message 102 of 104 (443667)
12-26-2007 11:16 AM
Reply to: Message 101 by RAZD
12-26-2007 10:39 AM


Re: The neo-lamarckian mechanism
--------------------------------------------------------------------------------
Evolution of ontogeny: linking epigenetic remodeling and genetic adaptation in skeletal structures | Integrative and Comparative Biology | Oxford Academic
The rest of your post - where you show how this applies specifically to Galapagos finches and how it is "neo-lamarkian" - is strangely missing.
No, what is strangely missing is your ability to take empirical facts, accept their inescapable implications, and revise your theoretical assumptions about the mechanisms involved in phenotypic alterations/epigenetic inheritance.
In this particular case, the expansion of the _average_ beak size of a particular population of finches on a particular Galapagos island when affected by the behaviour required to processer larger and tougher forage, temporarily, along with the decrease back to to normal _average_ beak size once normal-sized forage became once again available.
RM+NS? My aunt Fanny!

This message is a reply to:
 Message 101 by RAZD, posted 12-26-2007 10:39 AM RAZD has replied

Replies to this message:
 Message 103 by RAZD, posted 12-26-2007 2:13 PM Elmer has replied

  
Elmer
Member (Idle past 6022 days)
Posts: 82
Joined: 01-15-2007


Message 104 of 104 (443833)
12-26-2007 11:00 PM
Reply to: Message 103 by RAZD
12-26-2007 2:13 PM


Re: The neo-lamarckian mechanism
Hi RAZD;
You say;
quote:
what is strangely missing is your ability ...
Don't need to go all snooty. All you posted was a cut and paste, no link and no commentary for how it applies: this is against the forum guidelines.
First, it's a bit ironic,-- you complaining about what I say when what I say is framed in the exact same language as your comment, the one to which I am responding.
Second, I did not have a web link to my citation, because my source did not provide one. However, the original source, authors etc., is given right under the heading, and I should have thought that would be sufficient accreditation. Does this website require that all cited material must provide a working web link? Material from books and journals need not apply?
Third, commentary is redundant when facts speak for themselves--or am I to presume that every reader in this forum is an imbecile who needs the obvious spelled out for him/her? The facts in the citation are clear and definite; the facts about what occurred to the beaks of the finches in the famous Grants' study should be well known to anyone who has read this thread to this point, let alone to anyone who has contributed to the discussion. These two sets of facts correlate positively to very high degree wrt to neo-lamarckism, whereas the supposed 'selection' explanation given by the Grants and applauded by darwinists worldwide has never been anything but notional speculation derived post hoc.
Now the speculation has met with empirical science, and guess which one can't fly?
Yet you have not shown that genetic inheritance does not apply ...
The paper _does_ show that genetic inheritance does not apply- [except, perhaps, as some sort of jumping-off point]- in this study. The authors take pains to show that it is an epigenetic/proteomic and not a genetic mechanism that drives morphological/physiological development of the novel traits observed. It applies to bone, so why not cartilage, skin, feathers, fins, scales, and all else?
In short, there is no requirement for me to prove that something the paper treats as irrelevent, beside the point.
and even then you are still dealing with "inheritance" of hereditary traits in populations from generation to generation.
But that is not the issue. The issue is not stasis, i.e., "inheritance of hereditary traits in populations from generation to generation". The issue is the driving mechanism for "evolution", i.e., the change in the standard set of morphological, physiological, and instinctive behavioural traits in organisms over at least one generation. Epigenetic inheritance is an empirically proven fact. If epigenetic inheritance is a matter of the same trait appearing in two or more consecutive generations because the same stimulus and the same proteomic resonse to it persists over that period, then this paper explains how it operates. It also explains why the trait reverts to the standard form, a few generations after the environmental stimulus returned to normal. As was the case with the Grants' study. And here's a scary thought--just as was the observed [as opposed to the notional, 'bird predation'] case with the darwinists other favourite--the infamous 'speckled moth'.
You still don't show that the beaks are larger in the new chicks because they absorbed something from the ecology,
I do not have to "show" anything. This paper does the "showing".
But this paper says not one word about anything "absorb[ing] something from the ecology [sic]". Where did you get that idea?
What is does say is that their test organisms epigenetically developed their traits in response to environmental stimuli.
I relate that experience, since they are analogous, empirically speaking, first to the Grants' finches, and now to Majerus et al and the Peppered Moth.
rather than the tested "inheritance" of hereditary traits in populations from generation to generation.
I do not understand your meaning here. As above, 'inheritance' is inheritance'. and 'evolution' is 'evolution'. When people confuse the one for the other, they are wrong. And in the case of the finches, as in this entire forum, the subject is evolution.
Nor do you show that the beaks are larger in the parents because they grown that way in response to ecological conditions
I do not, as above, _have to show_ that the mechanism demonstrated by my cited paper does not apply to the finches, the moths , or anything else. The fact is that the mechanism which produces such phenomena is now empirically demonstrated, and is presumably ubiquitous. Compare this empirical mechanism as an explanation for the evolution to your metaphysical assumptions about it, and the onus falls on you to prove that your assumptions trump their science.
and then pass on that acquired trait to their offspring.
If the stimulating environmental conditions that epigenetically determined the developmental outcome of the parental trait persisted, it would do the same thing to the next generation, and if still persisting, the the generation after that. What is still unknown is the cause of the 'lag time', wherebye this mechanism does not cease operations the minute environmental stimuli revert to normal, but persists for at least a generation or two, as has been observed to be the case. The case of revertant eubacterial 'mutations' in their plasmid DNA may be connected to this as well. But as for now, we'll have to wait and see.
It's not a matter of accepting some "new paradigm" because it is missing.
It's not about what's missing [whatever it is you refer to]--it's about what's actually there.
Whatever way you cut the evidence, I am still left with:
... the change in hereditary traits in populations from generation to generation
Heredity is a fact. So what? Heredity is not the issue. Evolution is the issue. In this case the 'genes' did not evolve, they did not 'change' from generation to generation. The organism, however, did evolve. And so did every tested example of that genotype, generation after generation. Iterated change in a phenotype with no genetic mutation. That's what matters.
quote:
In this particular case, the expansion of the _average_ beak size of a particular population of finches on a particular Galapagos island when affected by the behaviour required to processer larger and tougher forage, temporarily, along with the decrease back to to normal _average_ beak size once normal-sized forage became once again available.
Yet the increase in beak size is not shown to have grown in response to the behavior\need for larger beaks.
First, the Grant study did not show, AFAIK, that any individual was born with a beak longer than that which was the established limit for normal beak sizes in that species. Only the _statistical average size_ in the overall population fluctuated.
The Grants themselves claim only that the _average beak size of the population_ increased directly because of mechanical requirements involved in eating larger, tougher forage. And that is not evolution; that is merely what farmers call pruning and culling, and darwinists call 'natural selection'.
At no point did the Grants connect the statistical alteration in the group phenotype to any genetic mutation. Evolution did not occur, except as an assumed statistical blip.
True, and I really wish that darwinists would stop doing that!! As for empirical evidence of a real biological mechanism, read the cited article. That's my scientific evidence.
What I got from the Abstract was that in some cases some bones grow somewhat differently due to epigenetic effects than probable from pure genetics.
By "pure genetics", do you mean what is predicted to happen under 'genetc determinsm'? IAC, I saw nothing in the abstract [I wish I had access to the whole paper]that referred to statistics. Simply to "BMP's", [bone morphogenetic proteins], which are empirical and ubiquitous, and above all, not 'genes'. Nothing about 'probability', either.
That may just mean that naturally large beaks can become somewhat stronger\larger than they otherwise would during the development of the chick to adult, but not that naturally small beaks can become as large as the naturally large beaks.
It doesn't mean that they cannot, either. If an epigenetic [proteomic]
mechanism can do a little, why can't it do a lot? And what does it matter,anyhow?
Yet you don't show that finches with small beaks do not die out during the drought conditions.
Why do I have to, even supposing that they do? That's nothing to do with anything!
So lets talk about:
'adaptation and variation' is the change in hereditary traits in populations from generation to generation
No, "adaptation and variation" are not "the change in hereditary traits in populations from generation to generation". How can you even think such a thing?
And return to the discussion of variation and adaptation with speciation added to the mix on Evolution and the BIG LIE? At least talk to Ray.
I am regularly talking to ray in that thread, and I'd be talking to you more often if you'd answer my questions. I was responding to your post 62 when it occurred to me that you only wanted to debate creationists, and so I asked you if you wanted me to drop out, since I am not a creationist. You never replied to that question, but after some time you addressed another post to me, so I assumed that you did want me to continue, and so I posted a response which ended with a request that you identify the particular points in the unfinished post 62 that you want me to respond to. So far as I know, you haven't done that yet.
If you want me to resond to everything in that long post it's going to take a lot of time and effort, but I'll do what I can with the time available to me. Just let me know what you want.
Edited by Elmer, : typoes

This message is a reply to:
 Message 103 by RAZD, posted 12-26-2007 2:13 PM RAZD has not replied

  
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