How Does Biological Evolution Deal With This?

[Jordan (Jordan Mantha)]

@Mercer

No, not a specific pattern, but it does have a leaf-shaped shield and pretty good color-matching.

Matching? The color varies substantially, does it not?

If you don’t see a specific pattern, why did you you claim that there was a “very specific and detailed pattern”?

The picture of Choeradodis rhomboidea in the OP seemed very specific (hence why I said it), looking at a google search of Choeradodis rhomboidea later I saw less specific examples (hence why I am now softening my statement). However, in my non-expert opinion, it still seems like very remarkable matching between the leaves that the insect is on and the insect itself. I was expressing a sentiment of awe, not making a particular scientific claim. It doesn’t seem quite as specific, but still remarkable.

@Mercer

want to know more, I’ve learned a lot, but it’s frustrating when I have questions and people jump down my throat for just expressing them or pushing my own understanding by dialogue.

In this case, you are making claims that you aren’t supporting. That is an odd way of trying to learn more.

Which claim(s) am I making? I don’t think I made any specific “claims” regarding the insect. All I’ve expressed is what I see when I look at it and that examples like this are hard for me to think about developing through long incremental steps.

@Mercer

And I am very skeptical of your claim. Would you please relate 10 of such observations and/or experiences? As a biologist, I find it very offensive.

Ah, well, I certainly didn’t mean it to be offensive. I apologize for that. Perhaps I was being a bit hasty in my language here. I certainly wasn’t trying to make a universal claim here.

@Mercer

So it doesn’t help if biologists downplay how incredible or unintuitive evolutionary science can be…

The claim was a categorical one about biologists downplaying. Do you even have a single example of a biologist doing that?

Note the “if” in there, I didn’t mean it as a universal statement. I guess I was, poorly, trying to defend the thread as a legitimate question. I also didn’t mean it in a personal or pejorative way. Take for example, the first response in this thread:

@Timothy_Horton

I’m curious as to how biologists unpack the presence of these kinds of adaptations:

What do you think needs unpacking? Insects with a coloring closer to the leaf’s green color had slightly better camouflage and a slightly better change of surviving to reproduce. The same with those more leaf-shaped than those without. After millions of generations of natural selection pressures you get insects with a remarkable ability to mimic the plants they live on.

@Rumraket

These kinds of adaptations are the very things natural selection explains.

Mantises are often exquisitely camouflaged, not only to escape predators but also to be able to jump on their unsuspecting prey. Their camouflage is used both defensively and offensively. They’re under a sort of double selective pressure, both from their natural enemies who eat them, and from the prey they stalk.

To me it seems like there is a lot to unpack. What specifically is changed in the insects biochemistry to make these changes? What DNA sequences are involved? What are the specific mutational steps throughout the insects evolutionary history that have led to that shape and color, etc? I’m not sure anybody knows, but it would be fascinating to know more.

But instead it’s just “natural selection”. Well sure, but that’s the kind of explanation I’m talking about. Natural selection is a very generalized explanation. It can account for just about anything, but doesn’t give the details. It’s this sort of glossed over explanation, intentional or (most likely) not, that I see as problematic. I’m not faulting @Timothy_Horton or @Rumraket by any means. I just wonder if there are more detailed, yet accessible, ways to talk about these kinds of questions.

@Mercer

Do you have the basic understanding that selection acts primarily on existing variation (corollary: without such pools of existing variation populations become extinct), and not the ridiculous creationist straw man that selection only acts on new mutations?

That makes sense, yes.

That’s a predictably mushy response. This is at the heart of what Darwinian evolution is, not some mere speculation. Misrepresenting this is at the heart of most deliberate and intentional misunderstandings of evolution; the next most frequent is pretending that neutral theory and evolution does not exist. I’ve found ignoring existing variation to be all but universal among evolution skeptics.

I really don’t quite understand what you’re getting at here. I never said natural selection was speculation or anything like that. Again, as I said to George, I have questions about evolution but I’m not questioning evolution. I’m not saying that evolution can’t account for the Choeradodis rhomboidea, I have simply asked questions about “how” because, to me, it seemed remarkable.

@Mercer

My questions are usually more along the lines of “where did this protein/DNA sequence/system come from?”

Maybe you don’t mean them this way, but your questions (particularly in this case) come off as the mushiest sort of “both sidesism” or calculated fence-sitting, and lack the chemical aspect I would expect from a chemistry professor. That’s why I challenge them, and since you never seem to stand by them, my impression is reinforced. You don’t seem to be trying very hard, particularly in this case, where you’ve made two strong claims from which you are backpedaling.

What sides are you talking about? Are you saying sometimes I seem like a creationist and sometimes an evolutionist? That could make sense. I was raised in YEC and most of my family are YEC/OEC. However, I don’t have a problem with evolution, and I’m not trying to disprove it or anything like that. I do have a lot of questions, and perhaps (frankly) ignorance as far as biology is concerned. I love that PS is a place where, generally, I can get a lot of great answers.

As far as “fence-sitting”, I’ll admit that my personality tends towards centrism and taking the best of various sides. Additionally, I try to be sensitive to the various positions and backgrounds of the students and faculty I serve. My own personal views are not the primary focus. My “fence-sitting” is, however, not disingenuous. I often do see good points on both sides of an argument and since I’m not an expert in biology or theology, I seek out expertise to help.

However, I just want to be clear. My questions in this thread are not trying to question evolution or natural selection. My questions are about how to understand in more detail how evolution and natural selection play out in terms of molecular/population genetics.

@Mercer

How about receptor-ligand interactions? The complexity of crosstalk is incredible. That would seem to be something that should interest a chemist.

That sounds great. I never had a biochemistry class in college and so I am trying to fill that gap as time allows. However, that wasn’t the topic of the thread so we should start a new one if we want to discuss that.

[Mercer (John Mercer)]

@Jordan

The picture of Choeradodis rhomboidea in the OP seemed very specific (hence why I said it), looking at a google search of Choeradodis rhomboidea later I saw less specific examples (hence why I am now softening my statement). However, in my non-expert opinion, it still seems like very remarkable matching between the leaves that the insect is on and the insect itself. I was expressing a sentiment of awe, not making a particular scientific claim. It doesn’t seem quite as specific, but still remarkable.

I’m saying that it’s remarkable and quite variable, not specific.

This gets to the aspect of evolution that I’ve been explaining that you don’t appear to grasp at all.

@Jordan

All I’ve expressed is what I see when I look at it and that examples like this are hard for me to think about developing through long incremental steps.

Those would be claims. Your difficulty is a product of your refusal to acknowledge existing variation as the primary substrate on which selection acts.

@Jordan

Ah, well, I certainly didn’t mean it to be offensive. I apologize for that. Perhaps I was being a bit hasty in my language here. I certainly wasn’t trying to make a universal claim here.

Apology accepted. I think you were trying to split the difference, which is bound to be offensive.

@Jordan

What are the specific mutational steps throughout the insects evolutionary history that have led to that shape and color, etc?

Good grief, Jordan. “Specific mutational steps” is the fundamental creationist misrepresentation of evolution.

So, to review:

@Mercer

Do you have the basic understanding that selection acts primarily on existing variation (corollary: without such pools of existing variation populations become extinct), and not the ridiculous creationist straw man that selection only acts on new mutations?

You: That makes sense, yes.

Jordan, how can you write, “That makes sense,” in response to my pointing out this misrepresentation, and then in the very same day invoke the same misrepresentation?

@Jordan

Take for example, the first response in this thread:

Timothy_Horton:

I’m curious as to how biologists unpack the presence of these kinds of adaptations:

What do you think needs unpacking? Insects with a coloring closer to the leaf’s green color had slightly better camouflage and a slightly better change of surviving to reproduce.

Tim is referring to existing variation, the very thing that you are implicitly denying exists.

@Jordan

To me it seems like there is a lot to unpack. What specifically is changed in the insects biochemistry to make these changes? What DNA sequences are involved?

What haplotypes are involved? Would new haplotypes require any new mutations?

@Jordan

What are the specific mutational steps throughout the insects evolutionary history that have led to that shape and color, etc?

Jordan, why are you invoking that creationist trope and implicitly denying the existence of existing variation?

@Jordan

I’m not sure anybody knows, but it would be fascinating to know more.

Why aren’t you interested in acknowledging the far greater magnitude of existing variation? Why aren’t you fascinated by recombination?

@Jordan

But instead it’s just “natural selection”.

Utterly false. As Tim noted, it’s natural selection acting primarily on existing variation, a mechanism you can’t bring yourself to acknowledge!

@Jordan

It’s this sort of glossed over explanation, intentional or (most likely) not, that I see as problematic. I’m not faulting @Timothy_Horton or @Rumraket by any means. I just wonder if there are more detailed, yet accessible, ways to talk about these kinds of questions.

The first step would be for you to acknowledge the importance of existing variation because it is far greater than the variation produced by new mutations. Why can’t you let go of that creationist trope?

@Jordan

I really don’t quite understand what you’re getting at here.

Then why did you say it makes sense?

@Jordan

I never said natural selection was speculation or anything like that.

We’re talking about your inability to acknowledge the existence and importance of existing variation.

@Jordan

I’m not saying that evolution can’t account for the Choeradodis rhomboidea, I have simply asked questions about “how” because, to me, it seemed remarkable.

So consider the ratio between existing variation and new variation and ask yourself why you’re pretending that only new variation (mutation) matters.

@Jordan

As far as “fence-sitting”, I’ll admit that my personality tends towards centrism and taking the best of various sides.

What is good about denying the existence of existing variation, exactly?

@Jordan

My questions are about how to understand in more detail how evolution and natural selection play out in terms of molecular/population genetics.

@Jordan

My questions are about how to understand in more detail how evolution and natural selection play out in terms of molecular/population genetics.

It’s hard to see how you can be thinking coherently about population genetics while simultaneously pretending that existing variation is not the major substrate upon which selection and neutral evolution act.

@Jordan

That sounds great. I never had a biochemistry class in college and so I am trying to fill that gap as time allows. However, that wasn’t the topic of the thread so we should start a new one if we want to discuss that.

I think your issues are far more basic.

@Mercer

To give you a metaphorical idea of its magnitude of this misrepresentation, if the size of the pool of existing variation in a mammalian species is a bathtub full of water, how much new water (mutations) is added per generation? Note that these numbers are real observational data, not conjecture.

Let’s call this ratio x, the ratio of existing variation to new variation from mutation. IMO, it is most vividly grasped as the ratio of the volume of a full bathtub to the volume of ___.

Your problem is that by not acknowledging the existence or the importance of this difference, you are a priori underestimating the speed/power/efficacy of evolution by a factor z that I would very, very roughly estimate as x < z < x^2.

So why aren’t you interested in knowing the empirically determined value of x, Jordan? Why do you repeatedly assume that it is zero?

[Jordan (Jordan Mantha)]

@Mercer

All I’ve expressed is what I see when I look at it and that examples like this are hard for me to think about developing through long incremental steps.

Those would be claims. Your difficulty is a product of your refusal to acknowledge existing variation as the primary substrate on which selection acts.

OK, maybe we’re getting somewhere. Perhaps I’m misunderstanding something and that’s causing you to interpret that as a “refusal to acknowledge”. I have no problem acknowledging existing variation. My understanding is that you have, throughout time, changing allele frequencies due to neutral mutation and natural selection. I’ve been thinking more about fixation rather than natural selection lately, but of course I recognize it is very important, especially in adaptation such as in this case.

@Mercer

What are the specific mutational steps throughout the insects evolutionary history that have led to that shape and color, etc?

Good grief, Jordan. “Specific mutational steps” is the fundamental creationist misrepresentation of evolution.

I realize that, but I’m not arguing whether evolution happened or not. That’s why I was confused by your response. Now, I think I understand a bit better what you’re saying. I was, frankly, thinking of “existing variation” as coming from mutations, I wasn’t thinking about recombination as you point out later. I’m not claiming that natural selection working on existing variation can’t be responsible for the shape and color of the insect. I’m just curious what genes are involved and how they have developed over time. How long did it take? I would have thought it would have taken quite a while but that’s really just a guess. What enzymes or regulatory code is involved? I just simply don’t know. I’m just not sure why my questions are seen as hostile when I’ve never said I was trying “disprove” or reject evolution.

@Mercer

Tim is referring to existing variation, the very thing that you are implicitly denying exists.

I didn’t realize I was doing that. I don’t have any problem with what Tim and Rum said, I was just trying dig deeper.

@Mercer

Why aren’t you interested in acknowledging the far greater magnitude of existing variation? Why aren’t you fascinated by recombination?

I am, I just wasn’t thinking about it when I was talking about steps. Recombination is really cool too.

@Mercer

The first step would be for you to acknowledge the importance of existing variation because it is far greater than the variation produced by new mutations. Why can’t you let go of that creationist trope?

I didn’t realize I was doing that, sorry. I certainly don’t have a problem existing variation, recombination, etc. I wasn’t intentionally ignoring it. My particular interests are the same regardless of whether they came from mutation or recombination. I’m just interested in how the DNA sequence changed through time to produce such an amazing creature.

@Mercer

I’m not saying that evolution can’t account for the Choeradodis rhomboidea, I have simply asked questions about “how” because, to me, it seemed remarkable.

So consider the ratio between existing variation and new variation and ask yourself why you’re pretending that only new variation (mutation) matters.

I’m not pretending, I just wasn’t thinking about it. I don’t care either way, I just wonder. I never said “it has to come from new variation and not existing variation”. I’m just wondering what is varying, and yes, secondarily it would be interesting to know what the source of the variation is. I don’t have any objection to either.

@Mercer

As far as “fence-sitting”, I’ll admit that my personality tends towards centrism and taking the best of various sides.

What is good about denying the existence of existing variation, exactly?

Yikes, we’re really are speaking past each other. I had no idea you were referring to “existence of existing variation” when you said I was fence-sitting. I thought you meant ID or something where I’m closer to Josh’s position (id not ID). I have absolutely no problem acknowledging the existence of existing variation.

@Mercer

That sounds great. I never had a biochemistry class in college and so I am trying to fill that gap as time allows. However, that wasn’t the topic of the thread so we should start a new one if we want to discuss that.

I think your issues are far more basic.

Potentially. I hate that my biology is so weak, but that’s a big reason I came to PS.

@Mercer

Let’s call this ratio x, the ratio of existing variation to new variation from mutation. IMO, it is most vividly grasped as the ratio of the volume of a full bathtub to the volume of ___.

Your problem is that by not acknowledging the existence or the importance of this difference, you are a priori underestimating the speed/power/efficacy of evolution by a factor z that I would very, very roughly estimate as x < z < x^2.

So why aren’t you interested in knowing the empirically determined value of x, Jordan? Why do you repeatedly assume that it is zero?

Well, I think this whole conversation could have been greatly shortened if it had gotten here at the beginning. I don’t know the answer to those questions, I’d be happy to know and know more about the timescales involved between existing variation and new variation from mutation. That’s why I asked the questions. I’m sorry they weren’t well-formed and that you thought I was intentionally disregarding or not acknowledging stuff. I just simply didn’t know. That’s why I wish stuff was unpacked more, rather than assuming I’m trying to avoid or not acknowledge.

[scd]

@gbrooks9

And so, in fact, if the Global Flood occurred sometime before or after the Pyramids of Giza were complete, you would expect thousands of human skeletons mingled with thousands of dinosaurs all buried and fossilized together in the vast confines of the Nile River Valley.

i actually dont talk about a flood here nor YEC position.

@Robert

Both those observations are evidence for evolution.

how exactly? its possible that different groups of creatures were made at different geological periods for instance.

@Faizal_Ali

No.

so what is your definition of out of place fossil?

@Faizal_Ali

That makes no sense. If the fact that fish are more abundant is the explanation, then we should not be finding land vertebrates anywhere, because fish were always more abundant.

no. since some fish species are less abundant than some species of land animals. the fish group as a whole is more abundant than land creatures since they have in general more species or individuals.

@Rich_Hampton

You didn’t read closely

you said that if a dolphin had a fish fin it will be out of place. so basically you are suggesting that evolution cant evolve a fish fin twice. but i dont think that evolution has such a limitation.

@Rich_Hampton

And if you took a look at this link : https://images.app.goo.gl/Jj5mJzTYgobGJHsz5 you can see quite clearly they are very different structures.

and yet they are also share some similarity. so i dont see a real distinction. actually even in homologous traits there is more difference and yet we need to believe that they are sharing a common structure:

(image from slideshareh)

[Robert]

@scd

Both those observations are evidence for evolution.

how exactly? its poossible that different groups of creatures were made at different geological periods for instance.

If one model predicts an observation and another model merely allow the observation then the observation is evidence in support of the first model. Evolution as a model predicts both faunal succession and correlation of successive faunas. Creation as a model doesn’t predict faunal succession - which is why YEC attempt (unsuccesfully) to argue against faunal succession. Creation of different groups of creature at different geological periods doesn’t predict correlation of faunas. Do you want to go all the way to a model (omphalic progressive creationism) of species being created just where and when they would have appeared due to evolution; you might as well go the whole hog and asset that the earth was created 6,000 years ago with the appearance of age.

[Faizal_Ali]

@scd

so what is your definition of out of place fossil?

A fossil that could not possibly exist if the theory of evolution was true.

@scd

no. since some fish species are less abundant than some species of land animals. the fish group as a whole is more abundant than land creatures since they have in general more species or individuals.

That would explain the situation is precambrian land vertebrates were less common than precambrian fish. It does not explain why there is not a single, solitary specimen of land organisms, period (never mind vertebrates) prior to the cambrian, then in later stages the abound.

Evolution accounts for this finding. Creationists attempt to account for it by saying the Global Flood neatly sorted the fossils out into layers like this. And then get offended when rational people laugh in their faces.

[scd]

@Robert

Creation of different groups of creature at different geological periods doesn’t predict correlation of faunas

why not? if for instance a group of reptiles were created at different time than a group of mammals, we should find them at different geological layers. so i see no real problem here. did you know that even according to the jewish tradition there might be several creation events too apart from what describe in genesis?

@Faizal_Ali

A fossil that could not possibly exist if the theory of evolution was true

ok but how we can recognize such a fossil if we will find it? how we test this idea?

[Faizal_Ali]

@scd

ok but how we can recognize such a fossil if we will find it? how we test this idea?

Why are you asking me? I’ve already said I do not accept the claim that a single fossil is sufficient to overturn the theory of evolution. There is just too many fossils that fall within the pattern that would be predicted by the theory.

Similarly, the fact that the platter on this turntable floats in midair is not sufficient to overturn the scientific claim that gravity exists. There is just too much evidence for the existence of gravity that we are obliged to seek another explanation.

How does the world's first "levitating turntable" actually work?

[gbrooks9 (GeorgeB)]

@Faizal_Ali

Why are you asking me? I’ve already said I do not accept the claim that a single fossil is sufficient to overturn the theory of evolution. There is just too many fossils that fall within the pattern that would be predicted by the theory.

@scd,

This is something I too have attempted to explain to you.

Evolution is supported in multiple sciences, with thousands of data points.

For some new information to overturn Evolution, you would need a pretty impressive pattern of data that is more than just a question mark … the pattern of data would have to contradict Evolution in such a way as to suggest an alternate theory.

Not even the theory of a Global Flood fills that bill. Fossils and chronological data certainly don’t corroborate any Global Flood scenario.

[Mercer (John Mercer)]

@Jordan

My understanding is that you have, throughout time, changing allele frequencies due to neutral mutation and natural selection.

Almost. Neutral evolution, not neutral mutation. Again, your fixation on de novo mutation is fueling a massive quantitative misunderstanding. You need to just (temporarily) put mutation off to the side to get over this huge block to understanding.

Remember that Darwin knew nothing of mutation. He was only seeing that there is variation in a population and that at least some of it is heritable (children tend to look like their parents). Mutation is not required to understand this, only these unremarkable and indisputable facts.

@Jordan

I realize that, but I’m not arguing whether evolution happened or not. That’s why I was confused by your response. Now, I think I understand a bit better what you’re saying.

I’m not sure you do. I apologize for any lack of clarity on my part.

@Jordan

I was, frankly, thinking of “existing variation” as coming from mutations,

Ultimately, it does. However, mutations may have occurred thousands or hundreds of thousands of years before the selective pressure, which is why you really, really need to abandon your fixation on it. It’s clear to me that you can only see mutation only coming after the change in selective pressure. That’s a fiction that blocks understanding.

@Jordan

I’m just curious what genes are involved and how they have developed over time.

Genes don’t develop. Organisms do.

@Jordan

How long did it take? I would have thought it would have taken quite a while but that’s really just a guess.

If you’re viewing it as dependent on new mutations, it would almost certainly be impossible. That’s the problem. If you knew the massive ratio of existing polymorphisms to new mutations, evolutionary time vanishes as an issue.

@Jordan

What enzymes or regulatory code is involved?

Many enzymes involved in pigment synthesis, packaging pigment into organelles, their movement around the pigmented cells (aggregation=lighter; dispersion=lighter), and tethering in the pigmented cells. All of these are almost unimaginably complex, highly dynamic processes that are easy to perturb.

I have no idea what you mean by “regulatory code.” Try to think much more about epistasis and recombination and much less about de novo mutations and residue changes. It’s much more complex and subtle than your intuition tells you it is.

@Jordan

I didn’t realize I was doing that. I don’t have any problem with what Tim and Rum said, I was just trying dig deeper.

OK, but please try to understand that from my perspective you appear to be trying to stay very, very shallow.

@Jordan

I am, I just wasn’t thinking about it when I was talking about steps.

That’s my point. Then by definition, you a) weren’t acknowledging it and b) you were ignoring it.

So, Jordan, think about what you currently intuitively see as the capability of evolution.

Multiply that by at least a million to better approximate reality. That’s x, roughly.

@Jordan

I certainly don’t have a problem existing variation, recombination, etc. I wasn’t intentionally ignoring it.

After having it pointed out to you, your nearly immediate repetition of the trope, then your quoting of a case of someone (Tim) pointing that very same thing out to you as an example of nonresponsiveness, I hope you can see that it is very hard for me to infer an absence of intent.

@Jordan

I don’t care either way, I just wonder. I never said “it has to come from new variation and not existing variation”.

I didn’t say that you said that. I explicitly characterized it as implicit.

@Jordan

I’m just wondering what is varying, and yes, secondarily it would be interesting to know what the source of the variation is.

Please try to understand that I’m not seeing much wonder. I think that to improve your understanding of evolution, keeping that magnitude of existing variation in the forefront of your mind is far more important than any curiosity about its source.

@Jordan

Well, I think this whole conversation could have been greatly shortened if it had gotten here at the beginning. I don’t know the answer to those questions, I’d be happy to know…

A million-fold, roughly; new mutation only provides a tiny 50-µl drop per generation added to a bathtub-sized reservoir of variation. Does that radically change your intuition about what evolution is capable of doing?

Now, drain the bathtub partially or fully through inbreeding. What becomes more likely as a result?

@Jordan

…and know more about the timescales involved between existing variation and new variation from mutation.

With diploids, the time scale has no limit. It’s something that we understand mathematically from population genetics. Again, the time scale is not nearly as important of the magnitude of the error that is fueling your skeptical intuition. It’s more than a million-fold.

@Jordan

That’s why I wish stuff was unpacked more, rather than assuming I’m trying to avoid or not acknowledge.

Please try to see my POV: you literally held up Tim’s unpacking for you (pointing out that you are ignoring the vast amount of existing variation available for selection) as an example of failing to unpack!

How should I interpret that?

[Jordan (Jordan Mantha)]

@Mercer

Almost. Neutral evolution , not neutral mutation. Again, your fixation on de novo mutation is fueling a massive quantitative misunderstanding. You need to just (temporarily) put mutation off to the side to get over this huge block to understanding.

Thanks for the correction, I think you are correct, in that when I think “something new in the DNA sequence” I just assume mutation. I will try to do better.

I was certainly not trying to dismiss “there is variation in a population and that at least some of it is heritable” but I may have not been thinking about all (or even the most important) sources of variation.

@Mercer

However, mutations may have occurred thousands or hundreds of thousands of years before the selective pressure, which is why you really, really need to abandon your fixation on it. It’s clear to me that you can only see mutation only coming after the change in selective pressure. That’s a fiction that blocks understanding.

This is super helpful. I’m aware of what you’re saying conceptually, but when it comes to application, I’m afraid I was defaulting to mutation → selection, mutation → selection, iteratively until you get a leaf colored/shaped insect.

@Mercer

Many enzymes involved in pigment synthesis, packaging pigment into organelles, their movement around the pigmented cells (aggregation=lighter; dispersion=lighter), and tethering in the pigmented cells. All of these are almost unimaginably complex, highly dynamic processes that are easy to perturb.

This is helpful (and along the lines of what I was looking for with my questions). When I see an insect that looks like a green leaf I might wonder if it has developed a way to produce chlorophyll, but I didn’t think that was probably it.

@Mercer

I have no idea what you mean by “regulatory code.” Try to think much more about epistasis and recombination and much less about de novo mutations and residue changes. It’s much more complex and subtle than your intuition tells you it is.

Well, I just literally have no idea what would be responsible for the insects leaf-shaped “shield”. It’s my understanding that gene regulation is often involved in that kind of thing.

@Mercer

I’m just wondering what is varying, and yes, secondarily it would be interesting to know what the source of the variation is.

Please try to understand that I’m not seeing much wonder. I think that to improve your understanding of evolution, keeping that magnitude of existing variation in the forefront of your mind is far more important than any curiosity about its source.

I think my curiosity here comes from my desire to understand more about how biological systems work. I really don’t know how you go from 1 cell to an organism. I’m not sure how an organism works. All my biology was either DNA → RNA → protein or conservation biology/ecology, I never got much of the middle about how cells work to form an organism. That’s why I’m curious.

@Mercer

A million-fold, roughly; new mutation only provides a tiny 50-µl drop per generation added to a bathtub-sized reservoir of variation. Does that radically change your intuition about what evolution is capable of doing?

Wow, that is amazing. I wouldn’t have guess that big of a difference.

@Mercer

Now, drain the bathtub partially or fully through inbreeding. What becomes more likely as a result?

I’m not exactly sure, but less variation at least, right?

@Mercer

Please try to see my POV: you literally held up Tim’s unpacking for you (pointing out that you are ignoring the vast amount of existing variation available for selection) as an example of failing to unpack!

How should I interpret that?

My point is, I can read what Tim said:

Insects with a coloring closer to the leaf’s green color had slightly better camouflage and a slightly better change of surviving to reproduce. The same with those more leaf-shaped than those without. After millions of generations of natural selection pressures you get insects with a remarkable ability to mimic the plants they live on.

and agree with it and still not know anything significant about how that insect got that way. Of course natural selection acting on variation, I didn’t think that was in dispute. But what are the variations? What’s actually changing in the insect? What happens if the environment changes, how quickly can it adapt? What did the insects along the way look like? Those are interesting questions. I know my initial question was about my lack of a good intuition about timescale. Tim, you, and others have pointed out better ways to think about it, and I’m thankful for the insight as that’s why I asked the question.

I had hoped that you had interpreted it they way it was meant, me trying to figure out some biology that was curious to me.

[Faizal_Ali]

@scd

and yet they are also share some similarity. so i dont see a real distinction. actually even in homologous traits there is more difference and yet we need to believe that they are sharing a common structure:

Do you understand the difference, illustrated in that figure, between homologous and analogous structures?

[Rich_Hampton]

@scd

you said that if a dolphin had a fish fin it will be out of place. so basically you are suggesting that evolution cant evolve a fish fin twice. but i dont think that evolution has such a limitation.

Yes it would be our of place. The dolphin ancestor had legs, which less bones then the fish fin. Consequently those bones were connected by a different musculature which enabled a different movement. Over generations the number of bones and muscles Changed little (if at all) but for proportions and attachment points.

Convergent evolution does not mean exactly the same structure evolved - a virtual identical, genetic twin - but that adaptations of existing but different structures resulted in an overall similar organ, limb, etc.

[Mercer (John Mercer)]

@Jordan

Thanks for the correction, I think you are correct, in that when I think “something new in the DNA sequence” I just assume mutation. I will try to do better.

Thanks. An easy way to do that is to abandon “new” and replace it with “different.”

@Jordan

This is super helpful. I’m aware of what you’re saying conceptually, but when it comes to application, I’m afraid I was defaulting to mutation → selection, mutation → selection, iteratively until you get a leaf colored/shaped insect.

Great. With that as an underlying assumption, it likely would be far too slow.

@Jordan

This is helpful (and along the lines of what I was looking for with my questions). When I see an insect that looks like a green leaf I might wonder if it has developed a way to produce chlorophyll, but I didn’t think that was probably it.

That’s how an Intelligent Designer might do it.

Here’s an online book that gives the basics in mice, which are the same as for us:
http://www.informatics.jax.org/wksilvers/

@Jordan

Well, I just literally have no idea what would be responsible for the insects leaf-shaped “shield”. It’s my understanding that gene regulation is often involved in that kind of thing.

Everything is usually involved: biochemistry, morphogenetic gradients, gene regulation, etc.

@Jordan

I think my curiosity here comes from my desire to understand more about how biological systems work. I really don’t know how you go from 1 cell to an organism. I’m not sure how an organism works.

We only understand parts of each.

@Jordan

I never got much of the middle about how cells work to form an organism. That’s why I’m curious.

That’s all analog.

@Jordan

Now, drain the bathtub partially or fully through inbreeding. What becomes more likely as a result?

I’m not exactly sure, but less variation at least, right?

Yes, but the result is generally extinction.

@Jordan

My point is, I can read what Tim said:

But Tim didn’t mention mutation.

@Jordan

But what are the variations? What’s actually changing in the insect? What happens if the environment changes, how quickly can it adapt?

I don’t know. I don’t have a source handy, but I know that for people, just with existing variation and no new mutations, if you sent a group of Scandinavians to Africa and vice versa, the allele frequencies and estimated selection coefficients predict that they’d switch colors in only 40 generations–that’s if the Africans had no access to vitamin D and the Scandinavians had no access to clothes.

[dga471 (Daniel)]

@Mercer

I don’t have a source handy, but I know that for people, just with existing variation and no new mutations, if you sent a group of Scandinavians to Africa and vice versa, the allele frequencies and estimated selection coefficients predict that they’d switch colors in only 40 generations–that’s if the Africans had no access to vitamin D and the Scandinavians had no access to clothes.

That is an incredible fact to know. Do you have a reference for this so I can dig deeper, @Mercer?

[scd]

@Faizal_Ali

Why are you asking me? I’ve already said I do not accept the claim that a single fossil is sufficient to overturn the theory of evolution. There is just too many fossils that fall within the pattern that would be predicted by the theory.

this is why i asked for definition. i want to check the claim that most fossils fit with the theory.

@gbrooks9

For some new information to overturn Evolution, you would need a pretty impressive pattern of data that is more than just a question mark … the pattern of data would have to contradict Evolution in such a way as to suggest an alternate theory.

we can say the same about ID so i dont see any difference. its also reject the claim by prof dawkins and others.

@Rich_Hampton

Yes it would be our of place.

so please show me the calculation that show why evolution cant evolve a fish fin twice.

@Rich_Hampton

Convergent evolution does not mean exactly the same structure evolved

the problem with this claim is that its a subjective and not an objective. there is no such limit under the evolution scenario. but please show me otherwise.

[Faizal_Ali]

@scd

this is why i asked for definition. i want to check the claim that most fossils fit with the theory.

You’ve already confirmed that they do. If you didn’t already accept that the vast majority of fossils “fit the theory”, you wouldn’t be able to pick the odd one or two out, here and there, that seem to be “out of place” to you.

[gbrooks9 (GeorgeB)]

@scd

we can say the same about ID so i dont see any difference. its also reject the claim by prof dawkins and others.

@scd,

I have no idea what your sentence [above] is supposed to mean.

[Faizal_Ali]

@scd

the problem with this claim is that its a subjective and not an objective.

Are you saying it is only a subjective claim that, say, the genome of a shark is different from that of a dolphin?

[Mercer (John Mercer)]

@dga471

That is an incredible fact to know. Do you have a reference for this so I can dig deeper, @Mercer?

Sorry, no, that’s why I prefaced it with “I don’t have a source handy.” I must emphasize that this is in no way a fact. It was an extrapolation based on facts.

I looked a bit more and could not find it. It is likely from the work of Nina Jablonski or someone citing her work. That would be the best place to start. Here is a sample:
https://www.pnas.org/content/107/Supplement_2/8962

One fact that is consistent with a 40-generation timescale is that southeast Asians, while they are darker than northeast Asians, have a lower correlation between skin color and UV exposure, but their ancestors migrated south only 3000 years ago.

An interesting outlying group is the Inuit, who are dark despite low UV exposure, but get a lot of vitamin D from their diet.

It’s also worth noting that east Asians and Europeans became lighter by different genetic pathways:

msl203.pdf