The Ghost of Lamarck "mutates" Darwins Adaptive plasticity


Adaptive plasticity was proposed in the 1960's however explanations for their apparent rapidity were not understood. Phenotypic costs should slow this process down. In the 1990's epigenetics was discovered making a better mechanism for adaptive plasticity in the term phenotypic plasticity.

Neo-Darwinian random mutations are changes in the DNA sequence that can occur spontaneously or be caused by environmental factors. These slow mutations in theory can be passed on to offspring, and if they are beneficial, they can help the organism survive and reproduce. Adaptive plasticity is the ability of an organism to change its phenotype, or physical appearance, in response to changes in these mutations due to the environment. This can be done through a variety of mechanisms, including changes in gene expression, protein production, and cell structure. Epigenetics is the study of how environmental factors can alter gene expression without changing the DNA sequence. This can be done through a variety of mechanisms, including DNA methylation, histone modification, and RNA interference.


Phenotypic plasticity is a much faster process than adaptive plasticity. This is because phenotypic plasticity does not require changes in the DNA sequence, which is a slow and error-prone process. Instead, phenotypic plasticity can be achieved through changes in gene expression, which is a much faster and more precise process.

Adaptive plasticity is a slower process because it requires changes in the DNA sequence. This is a slow process because it is limited by the rate of mutation. Additionally, mutations are often neutral or harmful, so it is rare for a mutation to be beneficial enough to be passed on to offspring. Epigenetic changes can be 100,000 times the speed of random mutations.

Phenotypic plasticity is a more efficient way for organisms to adapt to changes in their environment. This is because it allows organisms to respond to changes in their environment quickly and without the need for genetic changes. Additionally, phenotypic plasticity can be passed on to offspring, which can help to ensure that the offspring are better adapted to the environment than their parents.

Here are some examples of adaptive plasticity and phenotypic plasticity:

  • Adaptive plasticity: A population of bacteria that lives in a hot environment might evolve to have a higher tolerance for heat. This would be an example of adaptive plasticity because it requires changes in the DNA sequence. By the time a series of mutations occur it's likely the environment will have changed.

  • Phenotypic plasticity: A population of plants that lives in a dry environment might develop deeper roots to access water. This would be an example of phenotypic plasticity because it does not require changes in the DNA sequence. Instead, it is achieved through changes in gene expression.

Phenotypic plasticity allows organisms to respond to changes in their environment quickly thus allows organisms to adapt to a wide range of environments.

Epigenetic "phenotypic plasticity" can explain "adaptive plasticity." Epigenetic changes can explain why some organisms are more plastic than others. For example, some species of fish can change their sex in response to environmental conditions. This is an example of extreme phenotypic  plasticity. The ability to change sex is an adaptation that allows fish to survive in changing environments.

Epigenetic changes are an important part of Lamarckian evolution. They can help organisms to adapt to new environments, and they can explain why some organisms are more plastic than others.

Here are some additional examples of how epigenetic changes can lead to phenotypic plasticity:

  • In some animals, the amount of melanin in their fur or skin can change in response to sunlight. This helps them to regulate their body temperature and to camouflage themselves from predators.

  • In some plants, the amount of starch they store in their leaves can change in response to drought. This helps them to survive periods of dry weather.

  • In some insects, the size of their offspring can change in response to the availability of food. This helps to ensure that the offspring have the best chance of survival. This is not the survival of the fittest rather the arrival of the fittest.

There are many different phenotypic costs of adaptive plasticity. This points us to the conclusion that what we thought were adaptive plasticity were actually epigenetic phenotypic plasticity. Some of the most common costs include:

  • Production costs: These are the costs associated with producing a plastic phenotype. For example, it may take more energy to produce a larger body size, or it may take more time and resources to learn a new behavior.

  • Maintenance costs: These are the costs associated with maintaining a plastic phenotype. For example, a larger body size may require more food and water, or a learned behavior may require regular practice to keep it from being forgotten.

  • Mismatch costs: These are the costs associated with expressing a phenotype that is not well-matched to the current environment. For example, a plant that grows tall in a sunny environment may be more susceptible to wind damage if it is transplanted to a shady environment.

  • Ecological costs: These are the costs associated with the effects of a plastic phenotype on the environment. For example, a predator that learns to avoid a particular type of prey may reduce the population of that prey species.

  • Mutation costs. It takes vast amounts of times for mutations to accumulate. By the time they arise the original environment has likely changed.

These scientists say:

"If plasticity is adaptive, we would predict that the closer to fitness a trait, the less plastic it would be.

Our results showed, unexpectedly, that although traits differed in their amounts of plasticity, trait plasticity was not related to its proximity to fitness.

We caution against general expectations that plasticity is adaptive, as assumed by many models of its evolution.

From this initial set, we extracted data from 213 studies reporting reaction norms as a measure for plasticity.

Our results show that trait types did not correlate, as predicted, with how closely the traits were related to fitness but did differ in their amount of plasticity.

These results indicate that non-adaptive or potentially maladaptive responses in plasticity might be quite common.

We stress a need for caution related to the expectation that plasticity is adaptive and suggest a re-evaluation of the generality of conceptual work based on the assumption that most plasticity is adaptive."

https://royalsocietypublishing.org/doi/10.1098/rspb..0653

Epigenetic "phenotypic plasticity" can give the illusion  of "adaptive plasticity", but it is not the same thing. Adaptive plasticity is a NeoDarwinian mechanism, while epigenetics is a different mechanism that can also lead to phenotypic variation.

  • Adaptive plasticity is the ability of an organism to change its phenotype in response to its environment in a way that increases it's random mutations for natural selection to increase its fitness. This can be done through a variety of mechanisms, including changes in gene expression, protein production, and metabolism. 

  • Epigenetics is the study of changes in gene expression that are not caused by changes in the DNA sequence. These changes can be caused by environmental factors, such as diet, stress, and exposure to pollutants. Epigenetic changes can be inherited by offspring, but they are not permanent. They can be reversed by changes in the environment. Phenotypic plasticity allows organisms to adapt to changing environments more quickly than if they could only change their phenotype through genetic mutation.

Epigenetic changes can sometimes lead to phenotypic variation that is similar to adaptive plasticity. For example, if an organism is exposed to a nutrient-poor environment, it may develop a smaller body size. This smaller body size may be adaptive, because it requires less food to maintain. However, the smaller body size is not caused by a mutation in the DNA sequence. It is caused by an epigenetic change that affects gene expression.

Here are some additional points to consider:

  • Adaptive plasticity is a relatively recent discovery. It was not until the 1960s that scientists began to appreciate the importance of environmental factors in shaping the phenotype.

  • Epigenetic changes have been known for much longer. However, it was not until the 1990s that scientists began to understand how epigenetic changes can affect gene expression.

 So it's likely adaptive plasticity is actually epigenetic guided phenotypic plasticity.

Articles

Phenotypic plasticity and the origins of diversity

Mary Jane West-Eberhard

Annual review of Ecology and Systematics 20 (1), 249-278, 1989

>2593< citations!

Phenotypic plasticity is the ability of a single genotype to produce more than one alternative form of morphology, physiological state, and/or behavior in response to environmental conditions." Plasticity" and" development" are related terms that are becoming inŠ½ creasingly common in evolutionary biology and ecology. Both phenomena have passed through a period of neglect. In the 1960s Wigglesworth described some geneticists as being" apologetic" about environmentally cued polymorphisms, which they considered examples of unfortunate defects in the delicate genetic apparatus:" As R. A. Fisher once said to me, it is not surprising that such elaborate machinery should sometimes go wrong." And Bradsha noted that botanists were carefully avoiding any mention of plasticity; environmental effects in experiments were considered" only an embarrassment." Until recently, genetic considerations have been dominated in discussions of evolution and selection. Compared to the enormous progress made in genetics, there has been relatively little systematic effort to analyze environmental effects on the phenotype, and their evolutionŠ½ ary consequences. The plastic phenotype, stigmatized by poorly understood environmental influences and the ghost of Lamarck, has sometimes been lost from view as the focus of selection. Much recent progress has been made toward integrating developmental and evolutionary biology, especially in vertebrate morphology  developmental genetics  and molecular biology also see ." 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7004013/

https://pubmed.ncbi.nlm.nih.gov/24274594/


Comments

Post a Comment

Popular posts from this blog

Beyond the Sequence: The Epigenetic "Fingers" That Play the DNA Keyboard

Image
Imagine the keyboard itself is not a standard piano keyboard, but a modular synthesizer, capable of producing an almost infinite array of sounds. The DNA sequence, then, represents the fundamental building blocks of this synthesizer, the raw materials from which all sounds are generated. Epigenetics, our "fingers," manipulates these building blocks, adjusting parameters like volume, timbre, and rhythm, transforming the raw potential of the DNA sequence into a symphony of cellular functions. We can further refine the "fingers" analogy. Consider that each finger represents a distinct epigenetic mechanism: DNA methylation, histone modifications, and non-coding RNA.  DNA methylation, for instance, might be the "index finger," capable of precisely silencing specific genes, like muting individual keys on the synthesizer. Histone modifications, the "middle finger," could represent the ability to adjust the accessibility of the DN...
Read more

Why are Christian philosophers running towards Darwin while biologists are "running" away?

Image
As nature reveals the strength of epigenetics and the weakness of Neo-Darwinism, biologists are “running” away from the long-standing accepted theory. In The Federalist , April 2019, Benjamin Dierker reviews “Why one-third of biologists now question Darwinism”: "Current estimates are that approximately one-third of professional academic biologists who do not believe in intelligent design find Darwin’s Theory inadequate to describe all of the complexity in biology.” Dierker continues, “The important note is that these are not ideologues or religious zealots, nor do they propose a god or biblical solution.  Rather, they find problems in the lack of explanatory power of Darwin’s theory in light of modern understanding of mutation, variation, DNA sequencing and more. These expressions of doubt do not reject naturalism or evolution per se, but the rigor of the Neo-Darwinian model for explaining the development of life.” For 40 years, scientists calculated natural se...
Read more

Rewriting the Rules: Epigenomic Mutation Bias Challenges Randomness in Evolution

Image
This research challenges the long-held dogma that mutations occur randomly, irrespective of their consequences, by demonstrating a clear, epigenome-mediated mutation bias in Arabidopsis thaliana . The study meticulously unveils how mutation rates are not uniform across the genome but are significantly reduced in functionally constrained regions, particularly within gene bodies and essential genes. This discovery fundamentally alters our understanding of evolutionary processes, suggesting that mutation is not a purely directionless force. "Mutation bias reflects natural selection in Arabidopsis thaliana" This opening statement encapsulates the core finding: mutation rates are not random but reflect epigenetic pressures. The authors demonstrate that mutations are less frequent in crucial genomic regions, directly contradicting the prevailing theory of random mutation. This observation suggests an active mechanism that minimizes deleterious mutations in essentia...
Read more