- A recent study identifies phenotypic plasticity as the ability of tadpoles to change how they look and act, and how their tissues function, in response to their environment. If the pond also contains fairy shrimp, some tadpoles turn into aggressive carnivores and sometimes, the carnivorous tadpole stage becomes entrenched – without the need for a dietary trigger. This plasticity has also been confirmed in lizards, roundworms, and yeast. When yeast is exposed to the herbicide paraquat, the yeast copes by eliminating some or all of the DNA in their mitochondria, the cells’energy-producing organelles.
- Some consider this a classic example of “plasticity-first evolution”. On the surface, the findings vindicate Lamarck. The plasticity those changeable tadpoles display is built into their genetic code. And when an “acquired” trait does become “permanent”, it is because of mutations that “fixed” the plastic trait – a process biologists call genetic assimilation.
- Since plasticity is a built-in trait of so many organisms, it has obviously been mistaken for “evolution”. “Permanent” claim is meaningless given all organisms populations are ever-changing. The main questions are “what are the limits of plasticity?” and “what happens over the very long time?” The evidence to date is very clear:
a. Plasticity is a built-in widespread if not universal characteristic of organisms
b. It is limited in scope to a few traits like color, behavior, and metabolism
c. Plasticity is reversible rather than cumulative
d. It is not divergent as toads, lizards, roundworms, yeast, etc. never turn into not-toads, not-lizards, and so on.
- This is a repackaging of the same stories sold as proof of “evolution”. Darwin’s finches, the peppered moth, antibiotic resistant bacteria and, why not, the tanning humans. Too bad all these not only do not diverge into new organisms, but they all have been shown to revert eventually when the stimulus is removed. Finches change back their beaks depending on environment and never turn into non-finches, the black moths reversed to white and never to not-moths, antibiotic resistance disappears from the population when we reduce the use of antibiotics (see NIH recommendation), and neither light-skinned Nordics, nor dark-skinned Mediterraneans turn into not-humans under any circumstance.
This is a repackaging of the same stories sold as proof of “evolution”.
Sounds like a good names for bands.
I’m not sure cannibalistic tadpoles and matricidal worms should be taken as some kind of authority on the subject though.
The Science article linked above is a good read and there is nothing in it that justifies the “dispute evolution” claim.
Phenotypic plasticity is still determined by the DNA sequence of a genome, so it is entirely within the theory of evolution. Mutations can change the way in which phenotypes respond to environmental cues. Some of us tan more than others with the same amount of sun exposure, and that is because our genomes have different DNA sequences.
The author seems to misunderstand the basics of gene sequence vs. gene regulation.
That’s so … surprising! Nonlin didn’t understand? Just not possible!
I did enjoy the conflation of cases where there is high plasticity (tadpoles), well-understood genetically-determined plasticity (skin tone, rofl), and (I believe) no plasticity (melanism in moths).
The only person who should be upset by any of this is CharlieM. What does the tadpole archetype look like?
Yep. Welcome to TSZ.
The author’s surprise that an adaptation may be lost on removal of the adaptive pressure gives a good idea of their grasp of the subject.
Which theory of evolution?
Lacks compelling evidence yet it’s still part of “the theory of evolution.’
Par for the course. 🙂
The theory being used by the vast majority of biologists. You should study up on the lac operon, and understand how mutations in the promoter region and lac inhibitor would affect this classic example of phenotypic plasticity.
Scientists testing hypotheses is par for the course. ID supporters should look into it.
I could not find the part you quote. Where is it from?
Anyway, after reading the note, and the article that was being referenced, I don’t see where they say this is part of the theory of evolution. It looks much more as if they’re proposing that there’s a role for this kind of plasticity in evolution, thus it would be a hypothesis / proposal at best. I think it’s just too much speculation.
How did you gather that? Can you quote the source? Sciencemag thinks plasticity is “evolution’s” little helper – clearly a different phenomenon. You might also note them mentioning Lamarck, another clear counterexamples to your assertion.
So you think those are different? Can you explain? And more importantly, prove your assertion?
Where did you see that?
How so? Are you saying “Darwin’s finches, the peppered moth, antibiotic resistant bacteria and, why not, the tanning humans” are not examples of plasticity similar to those quoted by Sciencemag? Explain.
Did you read the part about Lamarck? How about “a powerful new helper”? Now, why would “evolution” need a “new helper”? Because it can’t stand on its own feet? Now, it would be naive to not read through the lines for the actual meaning of this “new” force of plasticity.
In the OP.
This is a excellent, excellent, thread. great points about plasticity .
i bumped into this with lizard studies some years ago.
its really indeed a great insight. In the few cases one can do actual science on THEY turn their bodyplans /or other matters into different ones without any claim of new mutations having been selected and new populations being created..
This ACTUALLY is likely the origin of species. With people or creatures/flora.
its a exosting option in the genes that is triggered after some threshold has been crossed.
This is not what Darwin wanted. this might be that lamarck dude.
in fact I don’t see why evolutionists would be happy about this and yet must admit these studies show these things.
Plasticity, evolutionists word, is not the word.
Its saying nothing about mechanism or about rejection of evolutionist mechanism.
Conversion was another thread here recently and this thread makes one of the best examples of why the wrong side should be converting.
When the scienbtific tests are done its not evolution but other things that change biological entities.
The year starts off great on TSZ. Well for creationists.
Well done thread. Beautiful. wHY NOT MORE POST EVERYBODY. never mind LOVE and CENSORSHIP or real malice problems.
This is the killer thread intellectually.
It would depend on whether or not the change was heritable – ie, the distinction is between adaptation by an individual (e.g. tanning) and a population.
Yes, I did. An enjoyable article well aimed, clear and not condescending to a lay audience.
A bit of hyperbole. This article contains less than some. Thanks, by the way for bringing it to my attention. I’ll keep an eye out for more articles from Elizabeth Pennisi. I see she has a degree in biology.
Hmm! That’s two questions. Is phenotypic plasticity a new helper? Does evolution need it? And, if yes to either, why? No, that’s three… I’ll come in again.
Map and territory issue. You, though you may not be aware of it are discussing a model of reality. I happen to think evolutionary theory, as far as I understand it, is a pretty accurate (comparatively, certainly) model of reality. My model might be incorrect and incomplete. Your model definitely needs attention.
Who’s naîve here? Doubt it’s Pennisi. Could be me. Or is it…
One thought for others to correct me on. With spadefoot toads, I see a process I find hard to differentiate from sympatric speciation in progress as in African lake cichlids.
How do you think phenotypic plasticity works? Every example I have looked at involves a protein sensing something in the environment which triggers some sort of signalling cascade that changes gene expression. The entire process depends on the DNA sequence of all the proteins and promoter regions involved. Change the sequence of the proteins that sense the environmental cue and you change the response to the environment. Change the DNA sequence of the signalling proteins further down the chain and you change the response. Change the sequence of the promoter regions and you change which genes are turned on or off at the end of the signalling pathway. From start to finish it is dependent on DNA sequence.
The modern theory of evolution. Period.
The DNA sequences that result in phenotypic plasticity are obvious targets for evolutionary change. That’s how the two are related. Mutations that change phenotypic plasticity can have beneficial, neutral, or detrimental effects.
Does this come with a testable hypothesis?
Yep. Here are 29 of them:
Do you understand the difference between a piece of evidence and a testable hypothesis? There are 29 pieces of 15 year old evidence in the article you posted some are no longer valid. All the same a piece of evidence is only a piece of the hypothesis. First you need to clearly state the hypothesis something I have not seen from the scientific crowd that is now denying Darwinian evolution.
If you actually read the material you would realize that each piece of evidence is framed within a testable hypothesis, complete with the prediction, confirmation, and potential falsifications.
You appear to think there is one single theory that can be called “the modern theory of evolution.” You’re in a position to know better.
That’s a different theory.
There are numerous smaller theories and hypotheses that make up the consensus view of how species change over time. This is the overarching model that we call the modern theory of evolution. Attaching names to the theory makes no sense and is a historical anachronism, especially for theories that are 150 years separated from the person who first proposed it.
Famous quote attributed to Theodosius Dobzhansky:
I think phenotypic plasticity actually hampers the speciation process. Plasticity is clearly adaptive in this case, so the plastic phenotype will be superior to either “static” phenotype.There is no disruptive selection driving the ecological separation of the incipient species, because the plastic phenotype allows the panmictic population to handle a wide array of environments.
The cichlids have another thing going that spadefoot toads have not (as far as I am aware): strong sexual selection maintaining prezygotic isolation between incipient species by female mate choice. Even if there were new incipient species of toads adapting to the different specific environments, the lack of assortative mating would quickly homogenize the genomes by recombination.
Ah, excellent. You have read up on phenotypic plasticity since our last discussion. I confess that I am a bit disappointed that this has not led to any insights in the difference between plastic and genetic changes.
Once again, the Carbonaria morph of Biston betularia is genetically determined, caused by a singular and recent mutational event, identified as a mutation by the insertion of a transposable element. As correctly pointed out by Jock and Allan, industrial melanism is not a plastic trait, nor are antibiotic resistance in bacteria nor are adaptations in beak morphology in Geospiza. All three require changes in the genetic composition of the population, contra your #2 and #3.
Yes, I see. It’s developmental triggers being pulled. Sex determination in Crocodilians due to temperature a similar situation?
In the sense that an environmental factor acts as a cue for some developmental trigger, yes.
There are a lot of examples like that, as many organisms need to cope with fluctuations in environmental conditions. In an earlier response to Nonlin, I mentioned polymorphism due to seasonal cycles. No sign of speciation in that example, as far as I know.
You have some serious reading comprehension issues.
Where is that distinction? All those organisms cited (and more) regress to the mean either as individuals or over generations. That means no “divergence of character” and that means no “evolution”.
Let’s add to that:
Is “evolution” related to plasticity at all?
What if plasticity is mistaken for “evolution” as in the many examples I provided?
How come all organisms are endowed with this ‘plasticity’ trait?
Why always ‘regression to the mean’ and never “divergence of character”? Can there be any “evolution” given the ALWAYS ‘regression to the mean’?
So? You’re not explaining anything. Where is the ‘plasticity’ in all that? Where are the limits of said ‘plasticity’? Why do all organisms regress and never “diverge”? How did you come up with: “so it is entirely within the theory of evolution”?
What does this even mean: “Mutations that change phenotypic plasticity”?
What about: “DNA sequences that result in phenotypic plasticity”?
Sorry, none of that was ever valid evidence.
What “difference between plastic and genetic changes”? You seem to think “genetic” is something magical with extra powers. But DNA and “the gene” are being downgraded. Even in the mainstream Evolutionistan.
You can’t HAVE evidence if you don’t have a testable hypothesis. What would you have evidence for? That’s right, the hypothesis.
All of it is still valid, without exception.
No, the evidence is not the hypthesis, nor a piece of it.
Bill do you know what evidence is? Try to describe in your own words what evidence is.
The hypothesis is that macroevolution has happened. Read the introduction:
Evolution, the overarching concept that unifies the biological sciences, in fact embraces a plurality of theories and hypotheses. In evolutionary debates one is apt to hear evolution roughly parceled between the terms “microevolution” and “macroevolution”. Microevolution, or change beneath the species level, may be thought of as relatively small scale change in the functional and genetic constituencies of populations of organisms. That this occurs and has been observed is generally undisputed by critics of evolution. What is vigorously challenged, however, is macroevolution. Macroevolution is evolution on the “grand scale” resulting in the origin of higher taxa. In evolutionary theory, macroevolution involves common ancestry, descent with modification, speciation, the genealogical relatedness of all life, transformation of species, and large scale functional and structural changes of populations through time, all at or above the species level (Freeman and Herron 2004; Futuyma 1998; Ridley 1993).
Universal common descent is a general descriptive theory concerning the genetic origins of living organisms (though not the ultimate origin of life). The theory specifically postulates that all of the earth’s known biota are genealogically related, much in the same way that siblings or cousins are related to one another. Thus, universal common ancestry entails the transformation of one species into another and, consequently, macroevolutionary history and processes involving the origin of higher taxa. Because it is so well supported scientifically, common descent is often called the “fact of evolution” by biologists. For these reasons, proponents of special creation are especially hostile to the macroevolutionary foundation of the biological sciences.
This article directly addresses the scientific evidence in favor of common descent and macroevolution. This article is specifically intended for those who are scientifically minded but, for one reason or another, have come to believe that macroevolutionary theory explains little, makes few or no testable predictions, is unfalsifiable, or has not been scientifically demonstrated.”
Now you’re getting somewhere. What if “speciation” is nothing more than plasticity “in disguise”? And drop the “sexual selection” nonsense. It’s circular logic.