[MOVED] The Extended Evolutionary Synthesis

[FrumiousBandersnatch]

The point I am making is that the EES forces don't just happen to produce variations that just happen to be adaptive. They are produced as a result of the creature/organism having made changes to the environment because they are in tune with the environment and nature so, therefore, know what is required to ensure they survive regardless of NS. If a mother creates a healthy environment for birthing and growth that produces fitness or cultures have practices that work with nature to produce an environment that gives a selective advantage then it's not as if NS can come along and do anything but go along with that.

What is being overlooked here is the ability of living things to be able to act in ways that can determine what is required for adapting and having a selective advantage. That the developmental processes only produce certain variations that are adaptive and give a selective advantage. That they are not random for a reason. They have already been determined as adaptive and having a selective advantage.

And it's not just because of past NS. Living things are not dumb passive creatures that are subject to some outside force of NS that limits their evolvability and survivability down to being changed to fit environments. They are interactive entities with their environments where they can anticipate changes and adjust accordingly and where developmental processes can be triggered by environments to produce non-random changes that are designed to help them adapt and survive. These are in tune with nature and thus produce what is needed to survive which is NS anyway. This is the fundamental difference between the EES and the SET in that the SET.

Creatures don't survive regardless of natural selection - it's the name for a process that involves preferential survival. Natural selection doesn't 'come along', it's there all the time; a selective advantage means an advantage in natural selection. The behavioural predispositions that lead to, for example, niche construction, are selected for - creatures that show those behaviours have a selective advantage, i.e. they're more likely to survive and pass on their predispositions; that's natural selection.

Natural selection and what you call the 'forces' of EES are not external agents manipulating organisms, they're names for ways of dividing up a set of complex interactions into conceptual categories that help us understand how populations change. Don't confuse metaphors and use of the intentional stance for reality.

 

[stevevw]

Just a thought: might you be to some extent conflating the popular definition of "random" (without purpose) with the scientific meaning (unpredictable)?

Is evolution according to the standard theory predictable

 

[Speedwell]

I disagree. If the variations are non-random then there will be a higher proportion of specific variations within certain parameters rather than if the variation were all random as per % of the source for that variation. This is the important distinction that differs from the variation produced from the EES forces as opposed to the way the SET views things.

That is not what I am talking about. Because of recombination, variation will be randomly distributed regardless of whether it has an intentional or predictable source or not. That's why the theory is called "the theory of evolution by random variation and natural selection," not random mutation and selection." Darwin observed randomly distributed variation in the phenotypes he was observing. He had no idea what caused it--none of that had been discovered yet.

 

[stevevw]

That is not what I am talking about. Because of recombination, variation will be randomly distributed regardless of whether it has an intentional or predictable source or not.

Ah I get you. Yes, that would be the case. But this doesn't really reflect how what type of variations are produced and therefore doesn't tell us anything about how the process of evolution can differ with those different types of variation.

What effect they will have on the process. What you are not considering is that under the EES variation can come from non-gene sources. So this is often not included under the SET. Most non-gene variation is non-random such as from EES forces like niche construction and inheritance beyond genes so this needs to be considered as sources of heritable variation as well.

That's why the theory is called "the theory of evolution by random variation and natural selection," not random mutation and selection." Darwin observed randomly distributed variation in the phenotypes he was observing. He had no idea what caused it--none of that had been discovered yet.

From what I have read most explanations describe evolution as being a combination of natural selection and random mutations. Darwin describes evolution as descent with modification. If we consider that there is suppose to be a universal common ancestor then there had to be new sources of variation introduced along the way.

Recombination is more about shuffling existing variation whereas mutation is about introducing novel variants. So most explanations including populations genetics usually only mention natural selection, mutation, random genetic drift, and gene flow as the mechanisms. But mutation is the only source of new variation that can evolve new species. Considering that mutation is random then this can add new variations beyond existing ones should widen the scope. But what we actually see is remarkable stasis.

 

[Speedwell]

Ah I get you. Yes, that would be the case. But this doesn't really reflect how what type of variations are produced and therefore doesn't tell us anything about how the process of evolution can differ with those different types of variation.

I'm not sure what you mean by "different types of variation." Variation is what it is, a randomly distributed range of phenotypes presented to the environment for selection with each new generation of a population..

What effect they will have on the process. What you are not considering is that under the EES variation can come from non-gene sources. So this is often not included under the SET. Most non-gene variation is non-random such as from EES forces like niche construction and inheritance beyond genes so this needs to be considered as sources of heritable variation as well.

From what I have read most explanations describe evolution as being a combination of natural selection and random mutations. Darwin describes evolution as descent with modification. If we consider that there is suppose to be a universal common ancestor then there had to be new sources of variation introduced along the way.

"Had to be" is not science, it's apologetics.

Recombination is more about shuffling existing variation whereas mutation is about introducing novel variants. So most explanations including populations genetics usually only mention natural selection, mutation, random genetic drift, and gene flow as the mechanisms. But mutation is the only source of new variation that can evolve new species. Considering that mutation is random then this can add new variations beyond existing ones should widen the scope. But what we actually see is remarkable stasis.

Is that supposed to make any sense? Maybe you should cite the source.

 

[stevevw]

I'm not sure what you mean by "different types of variation." Variation is what it is, a randomly distributed range of phenotypes presented to the environment for selection with each new generation of a population.

It is important to differentiate the different types of variation because this affects the way evolution will work. Not all variation is presented to the environment in the same way which will affect natural selections role. Under the EES niche construction for example a creature can change its environment rather than having to be adapted to the environment thus controlling its own evolution and natural selection.

The difference between the EES and the SET is if the variation is random then it is natural selection that becomes the driving force in evolution. But if the variation is non-random and already adaptive and heritable then it is the process that produced the variation that becomes the driving force in evolution rather than natural selection. These are two fundamentally different structures.

"Had to be" is not science, it's apologetics.

so what about this from a scientific paper.
Ultimately, the source of all variation must be mutation.
Sources of variation - An Introduction to Genetic Analysis - NCBI Bookshelf

'Must be' or 'has to be' are just a figure of speech and is more about making a factual statement based on a deductive assessment. That's unless you think that common descent is not part of evolution. If all life evolved from a common universal single-celled life then it is obvious that new variations had to have evolved to produce all the new species. Otherwise, a major scientific prediction of evolution is not fact and the theory is in trouble.

But this is all semantics. You still didn't respond to my point IE
What you are not considering is that under the EES variation can come from non-gene sources. So this is often not included under the SET. Most non-gene variation is non-random such as from EES forces like niche construction and inheritance beyond genes so this needs to be considered as sources of heritable variation as well.

Is that supposed to make any sense? Maybe you should cite the source.

As far as recombination only shuffling existing variations which does not add anything new. As opposed to mutations being the only source that adds new variations

For a given population, there are three sources of variation: mutation, recombination, and immigration of genes. However, recombination by itself does not produce variation unless alleles are segregating already at different loci; otherwise, there is nothing to recombine. Similarly, immigration cannot provide variation if the entire species is homo-zygous for the same allele. Ultimately, the source of all variation must be mutation.
Sources of variation - An Introduction to Genetic Analysis - NCBI Bookshelf
or here
Experiments to date indicate that recombination only shuffles already existing genetic variation and does not create new variation at the involved loci.
Talk:Genetic recombination - Wikipedia

For explanations for evolutionary mechanisms

The Hardy-Weinberg equilibrium principle says that allele frequencies in a population will remain constant in the absence of the four factors that could change them. Those factors are natural selection, mutation, genetic drift, and migration (gene flow).
Maintenance page

For random mutation being the only source of new variation and thus the basis for evolutionary theory along with natural selection.

Under the classical view, selection depends more or less directly on mutation: standing genetic variance is maintained by a balance between selection and mutation, and adaptation is fuelled by new favorable mutations.

Mutation is the ultimate source of all genetic variation, and is essential for evolution by natural selection: indeed, most of our genome has been shaped primarily by mutation and random drift.
Mutation and the evolution of recombination

As far as there being remarkable stasis in evolution

The fossil record provides abundant evidence that many species persist relatively unchanged for millions of years (Eldredge and Gould 1972; Barnosky 1987; Stanley and Yang 1987; Cheetham et al. 1994; Jackson and Cheetham 1999; Webster et al. 2003; Eldredge et al. 2005; Hunt 2007; Lieberman 2008; Geary 2009; Wiley and Liebermen 2011).
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It is a paradox that there is such stasis followed by the sudden appearance of species in evolution as Darwin said evolution should progress gradually in slight modifications building complex and varied life that has been on earth. Yet what we see in the fossil records are remarkable stasis. This supports what the likes of Gould, Lewontin, and the authors of EES are saying that most variation is not random but directed towards only a small set of variations in all living things and that creatures can direct their own evolution by changing environments to suit rather than being changed to environments which allows them to adapt and survive without major phenotypic changes.

 

[Speedwell]

It is important to differentiate the different types of variation because this affects the way evolution will work. Not all variation is presented to the environment in the same way which will affect natural selections role. Under the EES niche construction for example a creature can change its environment rather than having to be adapted to the environment thus controlling its own evolution and natural selection.

And how did the creatures develop tthe ability to build these niches? And you understand, I hope, that once the niche is constructed, it, too becomes part of the selective environment.

The difference between the EES and the SET is if the variation is random then it is natural selection that becomes the driving force in evolution. But if the variation is non-random and already adaptive and heritable then it is the process that produced the variation that becomes the driving force in evolution rather than natural selection. These are two fundamentally different structures.

What about adaptive, heritable variations which occur in the ordinary random distribution of variation? Are they not a "driving force in evolution as well?

But this is all semantics. You still didn't respond to my point IE
What you are not considering is that under the EES variation can come from non-gene sources. So this is often not included under the SET. Most non-gene variation is non-random such as from EES forces like niche construction and inheritance beyond genes so this needs to be considered as sources of heritable variation as well.

So you think EES processes produce a non-random distribution of variants? If the distribution of variants in the population doesn't form a bell curve, what curve do you think it forms?

As far as recombination only shuffling existing variations which does not add anything new.

But it is that shuffling process which gives rise to the bell-curve distribution of variants.

As opposed to mutations being the only source that adds new variations

I'm not sure we are talking about the same variations.

 

[stevevw]

And how did the creatures develop tthe ability to build these niches?

It is wrong to assume that the ability of creatures to change their environments under niche construction or the processes associated with other EES forces is the result of past natural selection. That is the assumption that the EES is trying to dispel ‘that all evolutionary change can be explained by the adaptive and selective view’.

As far as I know, research shows that natural selection alone cannot account for all evolutionary change. The evidence shows that processes associated with development and from the way living things behave and interact with their environments are also factors. There may not be an adaptive explanation that can explain all change that gives a survival advantage that is passed on. For example through developmental processes that produce only certain variation regardless of natural selection role.

The Modern Synthesis, Müller argued, leads scientists to look at these arrangements as simply the product of natural selection, which favors one variant over others because it has a survival advantage. But that approach doesn’t work if you ask what the advantage was for a particular species to lose the first toe and last toe in its foot, instead of some other pair of toes.
“The answer is, there is no real selective advantage,” said Müller.

The key to understanding why lizards lose particular toes is found in the way that lizard embryos develop toes in the first place. The key to understanding why lizards lose particular toes is found in the way that lizard embryos develop toes in the first place. A bud sprouts off the side of the body, and then five digits emerge. But the toes always appear in the same sequence. And when lizards lose their toes through evolution, they lose them in the reverse order. Müller suspects this constraint is because mutations can’t create every possible variation. Some combinations of toes are thus off-limits, and natural selection can never select them in the first place.
Scientists Seek to Update Evolution, Carl Zimmer

Plus some of the outcomes go against what would normally be considered a selective advantage that natural selection would preserve.

Niche construction processes can lead to the fixation of alleles that may otherwise be deleterious, it can facilitate the endurance of organisms in adverse environments and it can be beneficial despite being costly due to advantages that accrue for later generations [99].
Why an extended evolutionary synthesis is necessary

This comes down to the fact that under the EES the process that produces the variation can also be the same process that is producing the selective advantage that allows variation to be inherited. This means it cannot be defined as a single process as with natural selection but overall it is intertwined between the EES forces such as development processes, inheritance beyond genes and niche construction and natural selection.

Individuals learn from experience, which means that the variant that is expressed often depends on the environment (plasticity). Whether the variant is beneficial may depend on how ancestors modified the environment (selective niche construction). And behaviors, hormones and immune factors connect the phenotypes of parents with the development of their offspring (developmental niche construction or extra-genetic inheritance). Technically, what this means is that the processes that generate phenotypic variation (Lewontin condition 1) are causally intertwined with the processes that generate differences in fitness (condition 2) and the processes that generate heredity (condition 3).

The standard response at this stage is to point out that any adaptive directionality in evolution caused by plasticity, niche construction, and extra-genetic inheritance can, in fact, be explained by natural selection in the past. To be sure, natural selection is hard to escape so it is likely to be part of the explanation. But, if the Lewontin conditions are causally intertwined, one cannot move backwards in time and single out natural selection as an independent process, alone responsible for adaptation. And, therefore, one cannot invoke the proximate-ultimate distinction to refute alternative representations of evolution by natural selection. Doing so is to assume what is contested – that the Lewontin conditions are autonomous.

Failure to appreciate that how we choose to represent Lewontin’s conditions affects what counts as an evolutionary explanation appears to be a major source of communication failure surrounding the extended evolutionary synthesis.
How do living beings fulfil the conditions for evolution by natural selection? – Extended Evolutionary Synthesis

And you understand, I hope, that once the niche is constructed, it, too becomes part of the selective environment.

It depends on the environments. For example, insect nests are a closed system. They are an environment unto themselves. Ants for example can create a closed environment that is adaptive and produces fit offspring. Only the ants can produce this environment and this has nothing to do with natural selection changing the ant to suit the environment. It is the other way around, the ant changing the environment.

So I guess you could say it is the ants non-random ability that is doing the selecting and not natural selection. It is an environmental selection rather than a trait one. Yet it still provides heritable change. All creatures have this ability to a greater and lesser extent. It is the same for developmental bias as mentioned above. Certain changes are produced that are not up for sifting by natural selection. They just are what the development process produces because they are part of how the development programs work.

What about adaptive, heritable variations which occur in the ordinary random distribution of variation? Are they not a "driving force in evolution as well?

Yes of course. The EES doesn’t deny natural selection. It only claims that NS is one of several driving forces in evolution. But the point here is to expand the view of possible explanations as to how and when exactly NS and the other EES forces play their roles in evolution and not assume that it's just NS. It is often more complex and is a combination of these forces plus there are feedback loops where each force can influence the other.

So you think EES processes produce a non-random distribution of variants? If the distribution of variants in the population doesn't form a bell curve, what curve do you think it forms?
But it is that shuffling process which gives rise to the bell-curve distribution of variants.
I'm not sure we are talking about the same variations.

That depends on what is being measured. If we just measure all variations that are not going to tell us how each variable influences the outcomes. If you just measure current variation it doesn't include all possible variations that have happened throughout history. Adding them in will change results to perhaps a flatter curve (wider deviation).

But it can also be that comparing what variations actually persist may create a narrow deviation compared to all variations. It is not just a straight forward measurement of variation. The point is I think that out of all the possible variations that a random process can produce we seem to end up with a very narrow set of variations that doesn't support a random source of variation but rather non-random ones.

 

[Ophiolite]

As far as I know, research shows that natural selection alone cannot account for all evolutionary change.

That has been understood and accepted for roughly a century. Why do you even mention it?

 

[stevevw]

That has been understood and accepted for roughly a century. Why do you even mention it?

Because I was responding to the poster who claimed that all the EES processes like niche construction (the actions of creatures in providing adaptive environments) are the result of past natural selection which is the very assumption the EES is trying to dispel.

Plus if it has been understood for so long then why is there such debate about the EES. Why do the authors of the EES claim that despite the SET saying that this has been understood they still don't really incorporate this as an evolutionary cause. I've gone through this for many pages in this thread. Perhaps it would be best if you check them out.

If you check here #401 and here #407 this should explain things.

 

[Speedwell]

It is wrong to assume that the ability of creatures to change their environments under niche construction or the processes associated with other EES forces is the result of past natural selection. That is the assumption that the EES is trying to dispel ‘that all evolutionary change can be explained by the adaptive and selective view’.

Which doesn't answer my question:
How did the creatures develop the ability to build these niches?

As far as I know, research shows that natural selection alone cannot account for all evolutionary change. The evidence shows that processes associated with development and from the way living things behave and interact with their environments are also factors. There may not be an adaptive explanation that can explain all change that gives a survival advantage that is passed on. For example through developmental processes that produce only certain variation regardless of natural selection role.

The Modern Synthesis, Müller argued, leads scientists to look at these arrangements as simply the product of natural selection, which favors one variant over others because it has a survival advantage. But that approach doesn’t work if you ask what the advantage was for a particular species to lose the first toe and last toe in its foot, instead of some other pair of toes.
“The answer is, there is no real selective advantage,” said Müller.

The key to understanding why lizards lose particular toes is found in the way that lizard embryos develop toes in the first place. The key to understanding why lizards lose particular toes is found in the way that lizard embryos develop toes in the first place. A bud sprouts off the side of the body, and then five digits emerge. But the toes always appear in the same sequence. And when lizards lose their toes through evolution, they lose them in the reverse order. Müller suspects this constraint is because mutations can’t create every possible variation. Some combinations of toes are thus off-limits, and natural selection can never select them in the first place.
Scientists Seek to Update Evolution, Carl Zimmer

Plus some of the outcomes go against what would normally be considered a selective advantage that natural selection would preserve.

Niche construction processes can lead to the fixation of alleles that may otherwise be deleterious, it can facilitate the endurance of organisms in adverse environments and it can be beneficial despite being costly due to advantages that accrue for later generations [99].
Why an extended evolutionary synthesis is necessary

This comes down to the fact that under the EES the process that produces the variation can also be the same process that is producing the selective advantage that allows variation to be inherited. This means it cannot be defined as a single process as with natural selection but overall it is intertwined between the EES forces such as development processes, inheritance beyond genes and niche construction and natural selection.

Individuals learn from experience, which means that the variant that is expressed often depends on the environment (plasticity). Whether the variant is beneficial may depend on how ancestors modified the environment (selective niche construction). And behaviors, hormones and immune factors connect the phenotypes of parents with the development of their offspring (developmental niche construction or extra-genetic inheritance). Technically, what this means is that the processes that generate phenotypic variation (Lewontin condition 1) are causally intertwined with the processes that generate differences in fitness (condition 2) and the processes that generate heredity (condition 3).

The standard response at this stage is to point out that any adaptive directionality in evolution caused by plasticity, niche construction, and extra-genetic inheritance can, in fact, be explained by natural selection in the past. To be sure, natural selection is hard to escape so it is likely to be part of the explanation. But, if the Lewontin conditions are causally intertwined, one cannot move backwards in time and single out natural selection as an independent process, alone responsible for adaptation. And, therefore, one cannot invoke the proximate-ultimate distinction to refute alternative representations of evolution by natural selection. Doing so is to assume what is contested – that the Lewontin conditions are autonomous.

Failure to appreciate that how we choose to represent Lewontin’s conditions affects what counts as an evolutionary explanation appears to be a major source of communication failure surrounding the extended evolutionary synthesis.
How do living beings fulfil the conditions for evolution by natural selection? – Extended Evolutionary Synthesis

It depends on the environments. For example, insect nests are a closed system. They are an environment unto themselves. Ants for example can create a closed environment that is adaptive and produces fit offspring. Only the ants can produce this environment and this has nothing to do with natural selection changing the ant to suit the environment. It is the other way around, the ant changing the environment.

So I guess you could say it is the ants non-random ability that is doing the selecting and not natural selection. It is an environmental selection rather than a trait one. Yet it still provides heritable change. All creatures have this ability to a greater and lesser extent. It is the same for developmental bias as mentioned above. Certain changes are produced that are not up for sifting by natural selection. They just are what the development process produces because they are part of how the development programs work.

Yes of course. The EES doesn’t deny natural selection. It only claims that NS is one of several driving forces in evolution. But the point here is to expand the view of possible explanations as to how and when exactly NS and the other EES forces play their roles in evolution and not assume that it's just NS. It is often more complex and is a combination of these forces plus there are feedback loops where each force can influence the other.

That depends on what is being measured. If we just measure all variations that are not going to tell us how each variable influences the outcomes. If you just measure current variation it doesn't include all possible variations that have happened throughout history. Adding them in will change results to perhaps a flatter curve (wider deviation).

Stop the presses! Hold the front page!

But it can also be that comparing what variations actually persist may create a narrow deviation compared to all variations. It is not just a straight forward measurement of variation. The point is I think that out of all the possible variations that a random process can produce we seem to end up with a very narrow set of variations that doesn't support a random source of variation but rather non-random ones.

Here is a fact for you. Make of it what you will.
Let us consider, for purposes of a thought experiment, the adult height of a giraffe. If you measure the adult height of a population of giraffes and plot the results, they will form a bell-shaped curve. Given the shape of the such a curve, you can see that most giraffes will be at or near the average height, with a few being much taller or shorter than average. That difference in height is called variation. And the bell-shaped curve is called by mathematicians a random distribution. Therefore we say that the adult height of giraffes exhibits random variation. Darwin observed this randomly distributed variation in populations of living creatures, which is why he called his theory "The Theory of Evolution by Random Variation and Natural Selection.

 

[FrumiousBandersnatch]

Here is a fact for you. Make of it what you will.
Let us consider, for purposes of a thought experiment, the adult height of a giraffe. If you measure the adult height of a population of giraffes and plot the results, they will form a bell-shaped curve. Given the shape of the such a curve, you can see that most giraffes will be at or near the average height, with a few being much taller or shorter than average. That difference in height is called variation. And the bell-shaped curve is called by mathematicians a random distribution. Therefore we say that the adult height of giraffes exhibits random variation. Darwin observed this randomly distributed variation in populations of living creatures, which is why he called his theory "The Theory of Evolution by Random Variation and Natural Selection.

And, of course, the random variation is not a random selection of all conceivable variations, but only those variations that random changes to a specific pattern-generating mechanism can produce.

 

[stevevw]

Which doesn't answer my question:
How did the creatures develop the ability to build these niches?

I guess they just learned. Just like humans learned to build shelters. As to how this happened originally who knows as that is like asking the chicken and the egg question. We can make some assumptions but we cannot be sure.

One thing that does come out of the research is that creatures have had the ability to build niches for a very long time. Even creatures like insects and organisms like worms. So the ability may have been around since the Cambrian period.

Stop the presses! Hold the front page!

As mentioned before the authors pointed out that there is a difference between the mainstream view (SET) and the EES. The SET takes a more narrow view mainly focusing on adaptive/selective processes hence the expanded pluralistic view of the EES. The way a person views evolution will influence how they explain things and the assumptions, and predictions made. This is what the EES is trying to point out which people fail to see.

Failure to appreciate that how we choose to represent Lewontin’s conditions affects what counts as an evolutionary explanation appears to be a major source of communication failure surrounding the extended evolutionary synthesis.

Here is a fact for you. Make of it what you will.
Let us consider, for purposes of a thought experiment, the adult height of a giraffe. If you measure the adult height of a population of giraffes and plot the results, they will form a bell-shaped curve. Given the shape of the such a curve, you can see that most giraffes will be at or near the average height, with a few being much taller or shorter than average. That difference in height is called variation. And the bell-shaped curve is called by mathematicians a random distribution. Therefore we say that the adult height of giraffes exhibits random variation. Darwin observed this randomly distributed variation in populations of living creatures, which is why he called his theory "The Theory of Evolution by Random Variation and Natural Selection.

Yes but this doesn't really capture how variation works with the EES in evolution as a whole. For example, though there may be an average height of giraffes that fall into a bell curve that range of variation is still within a narrow range if the source of variation was truly random. The height of those giraffes is influenced by development constraints. For example, all mammals only have 7 neck bones.

So giraffe despite having some variation within their species can only have 7 neck bones and this will limit their height regardless of randomness. If variation was random then why wouldn't there be other variations such as 8, 9, 6, or 10 possible neck bones? But it seems that only one option was produced out of all possible random variations.

So the variation you are talking about is not macroevolution but micro which is within a species where development has already determined the body structures. That is not what we are talking about as far as the process of evolution through natural selection winnowing out variations that give a selective advantage.

The variation Darwin seen was not just about variation within species. He saw that one species could gradually morph into another through tiny changes. He put that down to natural selection only. The EES is saying that other forces contribute to those changes besides NS.

But rather than the source of variation being just random under the SET because the EES forces are nonrandom they can be both the source of variation and the determining factor for making variation advantageous and hertiable.

 

[Speedwell]

So giraffe despite having some variation within their species can only have 7 neck bones and this will limit their height regardless of randomness. If variation was random then why wouldn't there be other variations such as 8, 9, 6, or 10 possible neck bones? But it seems that only one option was produced out of all possible random variations.

Because evolution of a trait can only occur if the trait exhibits reproductive variation. Once the number of bones in a vertebrate neck ceased to vary--something which happens when variation of the trait (in this case the number of neck bones) no longer results in reproductive advantage--then the number of bones is fixed. This occurred in vertebrates long before the proto giraffe arrived on the scene. But the length of the bones continued to vary and when a longer neck offered reproductive advantage it was the variation in the length of the bone which provided it. There is no known evolutionary mechanism which would allow an extra bone to just show up.

So the variation you are talking about is not macroevolution but micro which is within a species where development has already determined the body structures. That is not what we are talking about as far as the process of evolution through natural selection winnowing out variations that give a selective advantage.

Yes it is. Evolution is exactly that process. In reality, it is rather more complex than our simplified thought experiment about the giraffe, but you seem unable to grasp even that.

The variation Darwin seen was not just about variation within species. He saw that one species could gradually morph into another through tiny changes. He put that down to natural selection only.

Not natural selection only, but natural selection acting on randomly distributed variation. The variation has to be randomly distributed in the population(that is, plotted to a bell curve) or evolution won't work.

The EES is saying that other forces contribute to those changes besides NS.

And if that's all you were claiming about EES then nobody here would disagree with you about it.

But rather than the source of variation being just random under the SET...

I am not talking about the source of the variation, only about how it is exhibited in the phenotype--as a bell curve distribution of variants. The source of the variation and the mechanism by which it is produced is another question altogether. Keep in mind that Darwin himself had no idea what the source of the variation was, but he observed that it was randomly distributed.

...because the EES forces are nonrandom they can be both the source of variation and the determining factor for making variation advantageous and hertiable.

And heritable? That's just nonsense. All variation with evolutionary significance is heritable.

 

[FrumiousBandersnatch]

I guess they just learned. Just like humans learned to build shelters. As to how this happened originally who knows as that is like asking the chicken and the egg question. We can make some assumptions but we cannot be sure.

"... they just learned" is doing a lot of heavy lifting here - perhaps you could explain how you think a population that doesn't construct explicit niches 'just learns' to construct them?

Start with a simple example; say, a bacterial population that evolves from solitary and non-cooperative to quorum-sensing and making bacterial films. How would such a bacterial population 'just learn' to do it?

 

[stevevw]

Because evolution of a trait can only occur if the trait exhibits reproductive variation.

You’re overlooking the variation that doesn’t get passed on, that is not selected for. These are still variations as far as counting all possible variations that are thrown up for selection. Therefore you would think that if evolution is random then there would have to be many possible alternatives. But we don’t see that. We see just 7 neck bones appearing and remaining as the only variation and not changing.

Once the number of bones in a vertebrate neck ceased to vary--—

If they varied in the first place shouldn’t we see records of this. Mammals with other numbers of neck bones before 7 became the optimum number. We only seem to see one set of numbers from when mammals first appear.

something which happens when variation of the trait (in this case the number of neck bones) no longer results in reproductive advantage--then the number of bones is fixed.

I would have thought if there was no reproductive advantage then the variation would be weeded out by NS. Don’t you mean that there is variation stasis in that the variation proves useful, spreads through the populations, and due to suitability becomes fixed?

This occurred in vertebrates long before the proto giraffe arrived on the scene. But the length of the bones continued to vary and when a longer neck offered reproductive advantage it was the variation in the length of the bone which provided it. There is no known evolutionary mechanism that would allow an extra bone to just show up.

Therefore this is just the variation in size of an existing feature which is what happens anyway. This may also be the result of developmental plasticity.

Yes it is. Evolution is exactly that process. In reality, it is rather more complex than our simplified thought experiment about the giraffe, but you seem unable to grasp even that.

In what way is it more complex?

Not natural selection only, but natural selection acting on randomly distributed variation. The variation has to be randomly distributed in the population(that is, plotted to a bell curve) or evolution won't work.

So what happens when EES forces produce non-random variations that already have a selective advantage?

And if that's all you were claiming about EES then nobody here would disagree with you about it.

wait a minute, one of the main points the EES authors were saying is that mainstream evolutionary view (SET) took a narrow view of evolutionary change by only using an adaptive/selective approach based on natural selection being the sole force. So no you may agree that NS is not the only force (though I would like to know what exactly you mean by that). But it seems the general view does not agree so you cannot speak for all. This is one of the disagreements between the EES and the SET and one that the EES is trying to dispel that NS is the sole force. They further pointed out as mentioned that people may pay verbal recognition of other forces in evolution but don’t really apply it in the theory where the EES forces are seen as actual causes of evolution on par with NS.

I am not talking about the source of the variation, only about how it is exhibited in the phenotype--as a bell curve distribution of variants. The source of the variation and the mechanism by which it is produced is another question altogether. Keep in mind that Darwin himself had no idea what the source of the variation was, but he observed that it was randomly distributed.

I understand that but how is this relevant to the EES. It doesn’t tell us anything about how that variation got there which is part of the evolutionary process. Though you say it’s a separate question it isn’t really because those two processes are linked and influence the outcomes of evolutionary cause. When you say the variation is randomly dispersed for natural selection to test this is not a true picture of what happens and once again overlooks the EES forces.

If that randomly disperse variation is mainly the result of non-random processes then the variation already has a selective advantage and this will affect natural selections role. Rather than NS being the driver in determining whether variation has the selective advantage, it is the EES forces that are driving evolution and natural selection. That is a big structural change in how evolution works and will cause a new hypothesis and is a major difference in scientific assumptions and predictions.

And heritable? That's just nonsense. All variation with evolutionary significance is heritable.

Yes but when we are talking about all variation that is available for selection much will be non-beneficial. The SET view makes NS the major and sole force for a reason. That’s because it views variation as random which means there may be any possible variation which includes suitable and unsuitable ones and it is NS that will winnow out the bad and preserve the (beneficial) that can be passed on. So there is much variation that will not be heritable under the SET that needs to be included in any measurement of total variation.

Whereas under the EES variation is well integrated, beneficial, adaptive and, therefore heritable because it is determined by additional processes that are nonrandom making it more likely that the variation is going to be heritable. It is the creature who creates the beneficial and selective environment that ensures it is passed on. It is the developmental processes that produce well suited, integrated and heritable changes in response to environmental perturbations that then makes the variation heritable.

 

[FrumiousBandersnatch]

But we don’t see that. We see just 7 neck bones appearing and remaining as the only variation and not changing. If they varied in the first place shouldn’t we see records of this. Mammals with other numbers of neck bones before 7 became the optimum number. We only seem to see one set of numbers from when mammals first appear.

But we do see variation - manatees and two-toed sloths have six cervical vertebrae, and three-toed sloths have nine.

Btw - how would a bacterial population 'just learn' quorum sensing?

How did the yeast Saccharomyces cerevisiae 'just learn' to propagate itself by making fruit produce chemicals that attract fruit flies, on which it can hitch a ride on to pastures new?

 

[Speedwell]

You’re overlooking the variation that doesn’t get passed on, that is not selected for. These are still variations as far as counting all possible variations that are thrown up for selection. Therefore you would think that if evolution is random then there would have to be many possible alternatives. But we don’t see that. We see just 7 neck bones appearing and remaining as the only variation and not changing.

That is because the number of neck bones is not exhibiting reproductive variation, as I explained. However, the length of those bones is varying, and that's how our imaginary giraffe gets a longer neck.

If they varied in the first place shouldn’t we see records of this. Mammals with other numbers of neck bones before 7 became the optimum number. We only seem to see one set of numbers from when mammals first appear.

That's because the number was fixed before mammals appeared.

I would have thought if there was no reproductive advantage then the variation would be weeded out by NS. Don’t you mean that there is variation stasis in that the variation proves useful, spreads through the populations, and due to suitability becomes fixed?

The best I can say to your strangely worded question is, perhaps something like that--but don't hold me to it, because I'm not exactly sure what you mean.

Therefore this is just the variation in size of an existing feature which is what happens anyway.

Anyway? That's all there is. Variation in size or number of an existing feature.

This may also be the result of developmental plasticity.

No, it's not. I don't think you know what developmental plasticity actually is, but you like it because you think it's not "random."

In what way is it more complex?

More things have to change than just the length of the neck bones in order for a giraffe's neck to get longer.

So what happens when EES forces produce non-random variations that already have a selective advantage?

You haven't shown that EES forces produce non-random variation. Give me an example of reproductive variation which does not plot to a bell curve because of EES forces and we can continue the conversation.

I understand that but how is this relevant to the EES. It doesn’t tell us anything about how that variation got there which is part of the evolutionary process. Though you say it’s a separate question it isn’t really because those two processes are linked and influence the outcomes of evolutionary cause. When you say the variation is randomly dispersed for natural selection to test this is not a true picture of what happens and once again overlooks the EES forces.

Give me an example of reproductive variation which does not plot to a bell cure because of EES forces and we can go from there.

Yes but when we are talking about all variation that is available for selection much will be non-beneficial.

That will depend on how much the selection criteria are changing. In a stable environment, most of the individuals are near the central tendency of the distribution and will survive--only those on the 'tails' of the distribution will be sacrificed.

Whereas under the EES variation is well integrated, beneficial, adaptive and, therefore heritable because it is determined by additional processes that are nonrandom making it more likely that the variation is going to be heritable. It is the creature who creates the beneficial and selective environment that ensures it is passed on. It is the developmental processes that produce well suited, integrated and heritable changes in response to environmental perturbations that then makes the variation heritable.

When referring to variation "heritable" means that the variation has the potential for being inherited. It is not a statement of how likely it is that the variation will be passed on, only that it could be if it passes natural selection.

 

[stevevw]

But we do see variation - manatees and two-toed sloths have six cervical vertebrae, and three-toed sloths have nine.

I would have thought these were the exception and not the rule. The fact is there is a narrow set of variations which doesn't seem to point to a random source. If you say that one variation from the usual 7 neck bones is evidence of randomness then why not 5 or 8 or 9 as well.

Btw - how would a bacterial population 'just learn' quorum sensing?

How did the yeast Saccharomyces cerevisiae 'just learn' to propagate itself by making fruit produce chemicals that attract fruit flies, on which it can hitch a ride on to pastures new?

I think these are different as simple celled microorganisms display high levels of HGT to start with. IT seems simple life forms have a great ability to share genetic info and cooperate to help create conditions and environments that benefit them. But this may be similar to how more complex creatures work with changing environments in that there are feedbacks between environments and the way creatures can change at the cell and tissue level. Environmental pressures affect cells and tissues which can respond in ways that produce beneficial changes that help them adapt through development such as with plasticity.

 

[VirOptimus]

I would have thought these were the exception and not the rule. The fact is there is a narrow set of variations which doesn't seem to point to a random source. If you say that one variation from the usual 7 neck bones is evidence of randomness then why not 5 or 8 or 9 as well.

I think these are different as simple celled microorganisms display high levels of HGT to start with. IT seems simple life forms have a great ability to share genetic info and cooperate to help create conditions and environments that benefit them. But this may be similar to how more complex creatures work with changing environments in that there are feedbacks between environments and the way creatures can change where environmental pressures affect cells and tissues which can respond in ways that produce beneficial changes that help them adapt.

"Thought" and "think" dont cut it.